GXemul Code2

Minor update of the guest OS documentation.

Updated TODO.

Bogus hack to machine_evbmips.cc to let RTEMS print some boot messages (again?) for mvme5500.

Adding configure script detection of -Wextra -Wno-unused-parameter -Wcast-align.

Running 'make test' will now treat memory leaks as test failure (in debug builds only). Also fixing a memory leak (in an ugly way).

Adding check for -Wnon-virtual-dtor.

Fixes to allow build using GCC's -Wshadow. Adding detection of -Wcast-qual and -Wshadow to the configure script.

const fixes, enabling builds using GCC's -Wcast-qual.

Updating some notes on supported platforms, and how/where development is done.

Fixing flawed mymkstemp by also passing O_CREAT | O_EXCL (used on systems without mkstemp) (reported as Debian bug #574537). I have tested it on an Ubuntu machine; it enables Linux users of gxemul to use e.g. the -j command line option (which did not work before).