UI: minor fix to ensure the replay exists when needed

(cherry picked from commit 6873bd3736e88a2d059fa90a9eb34f818f069bbe)
UI: Initial support for saving and loading a debug session
* This saves a json document which links the initial trace file to a set of snapshots
* Edited / outdated / valid properties are stored with each snapshot so that the snapshot indicator in the UI can be restored properly.
* All 'rel_path' properties are relative to the location of the session file. This allows the trace file, session file, and session data folder be moved to a new location and still be loaded. Only relative paths are currently supported.

Future goals:
* Ideally, any state of the UI should be included in the session so that active tabs / drop-down selections / texture zoom settings / etc are restored when the session is loaded.
* Indications of which shaders are edited should also be included (after the UI itself supports indicators of these changes)
* The original trace file should NOT be changed when the initial snapshot is edited or if/when we support the insertion and removal of API calls, so any changes to the API calls should be stored in this session file as well.

(cherry picked from commit 8ede72592ca94d754442e3f097ba03b546047ab1)
vogleditor: Replace hardcoded Qt path with variables generated by cmake's Qt module
sl: Only check the vogltrace library for the architecture that will be used

So that we don't error out even if the other architecture is not built.
sl: Simplify the code that determines which vogltrace library to load (32 or 64)
Merge pull request #3 from andrewkww/fix_hardcoded_qt_path

vogleditor: Replace hardcoded Qt path with variables generated by cmake's Qt module
Merge pull request #4 from andrewkww/fix_sl_arch

sl: Only check the vogltrace library for the architecture that will be used
chroot name cleanup
voglcore: Add pthread as link library

This means any targets that use voglcore will automatically get pthread
include during linking. So we don't need to specify pthread in targets
that don't explicitly use them.
vogleditor: Add link libraries that are needed
Ignore backup files
Do not hardcode qmake executable, it should be found by the CMake itself.
Find the include directory for libunwind.h.

This allows finding libunwind that has been installed in a non-standard location
just by setting CMAKE_PREFIX_PATH.
Fix some missing libraries.
Make building of OpenGL tests and samples optional.
Add missing X11 libs
Merge pull request #5 from andrewkww/fix_vogleditor_link

Fix linking issue in vogleditor
Merge pull request #7 from Daft-Freak/patch-1

Add missing X11 libs
Merge pull request #8 from Daft-Freak/patch-2

Ignore backup files
Merge branch 'master' of https://github.com/stativ/vogl into stativ-master

Conflicts:
	src/vogleditor/CMakeLists.txt