Update libdshowcapture to the latest version
Fix cmake app package issue

Currently the Info.plist file names the app package as OBS.app and cmake
is trying to use 'OBS Studio.app'.  I renamed it to OBS for the time
being just because we don't currently have actual studio interface yet.
Rename cpack description summary (also fix typo)
Fix scene editing for device pixel ratios ≠ 1

Fixes #177
Remove unnecessary compiler flag
Add mac-window-capture