sim_core: correction to ld {rXYZ}

User supplied test seems to indicate that the avr writes data to
 the destination register AFTER updating the index register.
  whereas the core originally read the index register and
  immediately stored the result into the register and then wrote
  back the index register.

If the code used: LD XH, X test indicated XH would return the
 value loaded from the indirect load operation versus the updated
 XH:XL value as the core originally assumed.

	modified:   sim/sim_core.c
fix gdb error message: Cannot remove breakpoints because program is no longer writable.
Fix avr_global_logger_get() decl  to not warn

When using sim_avr.h with a project that uses -Wstrict-prototypes, you
will get a warning that the prototype for avr_global_logger_get() is not
valid. Functions that take no args must explicitly use void to not warn.
Merge pull request #45 from cardoe/prototype-warning

Fix avr_global_logger_get() decl  to not warn.
Merge pull request #53 from nnayo/gdb_fault

fix gdb error message: Cannot remove breakpoints because program is no l...
make: Allow override of root path

Allows inclusion of Makefile.common from out of tree.

Signed-off-by: Michel Pollet <buserror@gmail.com>
test: Fix coroutine on old gcc

Removed traling colon. Fix issue #34

Signed-off-by: Michel Pollet <buserror@gmail.com>
cores: Fix mega2560

Added EIND, as per nnayo's. Also renamed the file to match the other
cores

Signed-off-by: Michel Pollet <buserror@gmail.com>
Merge pull request #59 from bsekisser/ld-st-rXYZ-bugfix

sim_core: Fix for issue #46, correction to ld {rXYZ}