change name of RP-specific components to mention RP
replace QSplashScreen with standard window:

* QSpashScreen is currently borked with retina displays (non-centered)
* This approach works on my retina Mac - need to test with non-retina
  and RP.
Allow chord to take opts:

 - although do nothing with them for now, just don't throw an error if
   they are there. Flexibility over unnecessary strictness.
update Qt build artifacts:

* remove QScintilla lib paths in .pro file.
* change target to Sonic-Pi
* add new qrc file
* update splash images - also new retina-ready image