More debugging features

[vhotspur]

Copying this as-is from a TODO file (there is no context whether this refers to emulated memory, some part of some student assignments or MSIM's use of malloc):

add debug features
 - memory allocation
 - first and last block check
 - show all allocated memory blocks
 - check for unallocated memory at the end of the program or at the free function call
 - allocation information (function, file and the line number)