move mruby's showcallinfo into the core
show a backtrace when when an error occurs on gem load; close #1243
forgot to add src/backtrace.c
Fix early free of irep->filename
Allow mrbc command options to be changed
Add example of modifying mrbc options to add debug info
Fix off by one issue
add comments for mruby-array-ext
Merge pull request #1253 from skandhas/pr-add-comments-for-array-ext

add comments for mruby-array-ext
Merge pull request #1252 from carsonmcdonald/fixfilenames

Fix for issue 1243
mrbc to take multiple files, preserving debug information if -g given; close #1243
Fix compiler warning by exiting if wfp isn't set
Merge pull request #1255 from carsonmcdonald/mrbcoutwarnfix

Fix compiler warning by exiting if wfp isn't set
First implementation of ObjectSpace moved outside of gc.c
Changed the object_count so that it only iterates over the RBasic object, not the full RVALUE known by the GC
Removed debug output
Changed the each_object callback so that a pointer is passed for the object, instead of the struct.
Minor formatting change.
Changed the counting so that only objects that are alive are added to the object counts.
Fixed the each object callback to be more consistent with other callbacks.