Misc fixes; Hershey fonts support; Static display frames support

[kamalmostafa]

• Build fixes resolves bug marcan/openlase#7 and adds "make install" functionality

Hershey fonts support:

• Font engine olGetFont() framework allows for new font types
• Hershey fonts support via libhersheyfont, if that library is installed: http://www.whence.com/hershey-fonts https://github.com/kamalmostafa/hershey-fonts Note: the simplest Hershey font ("futural") traces considerably faster than the OpenLase built-in default font.
• new demo app 'spin-text' (works with default or Hershey fonts): https://www.youtube.com/watch?v=8y04_yhh-ZM
• new demo app 'show-text' (works with default or Hershey fonts).

Static display frames support:

• Enables support for asynchronous calls to olRender() without requiring any olRender-loop, allowing for easier integration into existing code bases. This is the model used in my OpenLase back-end for UCBLogo: http://www.youtube.com/watch?v=oo7A1fPmPiE https://github.com/kamalmostafa/ucblogo

[kamalmostafa]

Rebased this patch set, and added two new build fixes:

• commit 12574cb fixes the build breakage introduced by commit 3fd071e "Update qplayvid to newer ffmpeg APIs"
• commit dc6ad29 reverts needless duplicate elf section redeclaration

[kamalmostafa]

I have rebased this patch set:

• new version of commit 5855217 fixes the build breakage introduced by commit 3fd071e "Update qplayvid to newer ffmpeg APIs"