Renamed library to GUIslice

• Renaming of library from microSDL to GUIslice complete
• Migration Notes (from v0.5):
  • Rename include files "microSDL_" to "GUIslice_"
  • Rename API calls from "microSDL__" to "gslc__"
  • Rename data types from "microSDL__" to "gslc__"
  • Rename constants from "MSDL__" to "GSLC__"
  • Rename constants from "MSDLX__" to "GSLCX__"

Separate rendering layer from core library

Separate rendering layer from core library

• SDL1.2 functionality has now been partitioned into a driver
  layer (microsdl_drv_sdl1) to facilitate the support for other
  graphics drivers in future releases.
• The microSDL core is now largely a platform-independent GUI (PIGUI)
• Created base types to replace SDL data types
• Add support for optional glow enable
• Optimized line drawing speed
• Migration notes:
  • Drawing routines (Line, FrameRect, etc.) are now all prefixed
    by Draw (eg. microSDL_Line becomes microSDL_Draw).
  • One driver layer needs to be included in compilation (eg. microsdl_drv_sdl1 for SDL1.2)

Major revision of library architecture

• Substantial updates have been done to enhance functionality
  and arrange the code structures in a hierarchical,
  object-oriented manner. Many APIs have been adjusted;
  please refer to the application examples for details.
• Added support for pages (tsPage). Pages are redrawn
  independently, so only elements on active pages are processed.
• Added support for element collections (tsCollect). Collections
  are the base unit for pages and compound elements.
• Compound elements now leverage much of the core framework
  code, making it easier to build advanced widgets.
• Added support for element timer / tick callbacks.
• Many other fixes and enhancements.