Gcode: simplify get_value with strtod
SimpleShell: use strtol to check for valid line limit instead of int(atof(...))
Merge branch 'edge' into track_allocs
Switch gcc4mbed.c license to Apache v2

I never meant for this to have a LGPL license on it.  I must have
copied that from MRI code base at some point.  I should have been
Apache v2.
Merge branch 'edge' into track_allocs

Conflicts:
	gcc4mbed/src/gcc4mbed.cpp
Check for double free with HEAP_TAG.

If you enable HEAP_TAG, now wraps free() calls to make sure it isn't
already freed and debugbreak()'s if it is.