Honor QUIET argument in FindJansson
Add initial implementation of a v4l2 capture plugin

This patch adds a plugin to capture video data from v4l2 devices under linux.
v4l2 plugin properties
added ability to choose device, pixel format, resolution
and frame rate
linux-xshm:  Fix cursor draw position

Due to the recent change with matrices, the way space is represented by
matrices is a bit different.  The matrix stack represents the view
matrix, rather than the model matrix, so the position is more
representative of the camera (view) itself, rather than that of the
objects (model).
Merge branch 'v4l2-input' of https://github.com/bazukas/obs-studio into bazukas-v4l2-input
Merge branch 'bazukas-v4l2-input'
Highlight label in properties-view when a disabled list item is selected
Unify obs_data_get* and obs_data_item_get* functions handling
Unify obs_data_set* and obs_data_set_default_* function implementations
Refactor set_item(_def) to only look up items if no item is supplied
Refactor obs-data internals to forward reallocation results to callers
Unify obs_data_set* and obs_data_item_set* funtion implementations
Move obs-data accessor value handling logic into static helper functions
Change semantics of obs-data default values

Default values are now permanently stored in the obs_data_items and
can be accessed via the new get_default functions

Also default values are no longer serialized to JSON to ease transition
to new default values
Add obs-data autoselect functions

These are meant to reflect auto-detection configuration changes that
should not be written to the config, for example, frame rate changes
for a camera where the (user-/config-file-)configured frame rate isn't
available but a similar frame rate can be automatically chosen
Make properties-view reflect autoselect settings (for property lists)
linux-xcomposite: Fix that the configuration is lost when source is recreated
Merge pull request #122 from reboot/fix_xcomposite_config_loss

Fix that the xcomposite configuration is lost when source is recreated
Merge pull request #121 from BtbN/fixes

Honor QUIET argument in FindJansson
Merge pull request #116 from palana/obs-data-changes

obs-data default value semantics change and autoselect value introduction