Cleanup: Libmv, clang-format

Is based on Google style which was used in the Libmv project before,
but is now consistently applied for the sources of the library itself
and to C-API. With some time C-API will likely be removed, and it
makes it easier to make it follow Libmv style, hence the diversion
from Blender's style.

There are quite some exceptions (clang-format off) in the code around
Eigen matrix initialization. It is rather annoying, and there could be
some neat way to make initialization readable without such exception.

Could be some places where loss of readability in matrix initialization
got lost as the change is quite big. If this has happened it is easier
to address readability once actually working on the code.

This change allowed to spot some missing header guards, so that's nice.

Doing it in bundled version, as the upstream library needs to have some
of the recent development ported over from bundle to upstream.

There should be no functional changes.

GLog: Lower default logging severity to INFO

Before this change messages of ERROR and above were printed.
This change makes it so LOG(INFO), LOG(WARNING), LOG(ERROR)
and LOG(FATAL) will be printed to the console by default
(without --debug-libmv and --debug-cycles).

On a user level nothing is changed because neither INFO nor
WARNING severity are used in our codebase. For developers this
change allows to use LOG(INFO) to print relevant for debugging
information. Bering able to see WARNING messages is also nice,
since those are not related to debugging, but are about some
detected "bad" state.

After this change the LOG(INFO) is really treated as a printf.
Why not to use printf to begin with? Because it is often more
annoying to print non-scalar types. Why not to use cout? Just
a convenience, so that all type of logging is handled in the
same way. When one is familiar with Glog used in the area, it
is easy to use same utilities during development. Also, it is
easy to change LOG(INFO) to VLOG(2) when development is done
and one wants to keep the log print but make it only appear
when using special verbosity flags.

The initial reason why default severity was set to maximum
possible value is because of misuse of VLOG with verbosity
level 0, which is the same as LOG(INFO). This is also why
back in the days --debug-libmv was introduced.

Now there is some redundancy between --debug-libmv, --debug-cyles
and --verbose, but changes in their meaning will cause user
level side effects.

Differential Revision: https://developer.blender.org/D10513

Libmv: Avoid use of LOG(INFO) in solver

Usage of LOG(INFO) actually went against own guidelines in the
logging.h: the INFO is for messages which are to be printed
regardless of debug/verbosity settings.

Tracking: Deal with gaps and long tracked segments better

When there is a gap during looking for a reference marker for the
scopes use the first marker after the gap. It helps re-positioning
the marker back in place after it got ocluded.

Also cosmetic changes on the labels.

Tracking: Implement previous/next keyframe scopes

The purpose of these scopes is to give more visual reference to a VFX artist:
this way the artist can (re)position the marker more accurately when it starts
to slide. Before this change it was always more of a guess work about where
exactly the marker was at the previous keyframe.

There are some weak aspects of the patch related on some rather annoying
duplicated lines about calling an utility function for each of 3 scopes.
Ideally there needs to be some sort of foreach scope utility, but it is not as
trivial as it sounds since the editors implementation code is in ED module,
which is not available by blenloader and blenkernel.

The interface aspects still needs some work. Currently it is 3 scopes placed in
one column. Maybe it needs to be a flow, or some collapsable box?

Differential Revision: https://developer.blender.org/D10567

Harden checks in datatoc_icon binary

The goal of the change is to perform check for attempts of icons
being overwritten on canvas. The check is based on checking original
coordinate of icons against all read icons. If there are two icon
files which have same original an error will be reported. The report
includes both file names to make it easier to troubleshoot.

This change will allow to early-on catch issues which we currently
have with the release environment: official Linux builds might have
different icon from Blender compiled locally. This is because the
order in which directory listing is traversed is not defined, so
it's like a race condition between two files to win the place in
the final canvas.

There is still possible improvement in the code to move more fields
into the context structure. This is beyond of goal of this change.

Note that before committing this change icons must be brought back
to their consistent state. Otherwise the build will fail.

Differential Revision: https://developer.blender.org/D9715

Cleanup: Spelling in comment

Cleanup: Tracking, reduce indentation level

Cleanup: Use more clear field name

Disambiguate which time the frames are measured in.

Fix T71960: Malformed .bmp files lead to crash

Add a boundary check, avoiding access past actual data.

Ideally would need to report error to the user somehow,
but it doesn't seem to be easy to do.

This is a minimal safe patch. The proper complete fix is
being worked on by Jesse.

Differential Revision: https://developer.blender.org/D10357