Improvements:

. Add schematic of EM6819 REva daughterboard version 2.0 in docs
. Add information about GCC4 in Getting Started doc:
    . Versions and official status
    . Spill mechanism
    . Empty sections limitation
. Add environment variables C816_GCC3_PATH and C816_GCC4_PATH.
    for scripts that need to select the version of the compiler.

Fixes:

. Various GCC4 compiler engineering fixes:
    . Give priority to indirect attribute over command-line option -mpage0-mvs
   . Make sure all zero-initialized variables go in bss (or page0_bss),
      not in data (nor page0_data) section
   . Prevent presence or absence of static keyword to affect the data/bss placement
   . Use software calls by default.
      For compatibility with old command-line project designed with GCC3.
   . Fix some compiler crashes.
. Watches: Corrected stacked variable display.