MSVC: compilation works again (+minor style fixes)
BUG: mrb_irep_free (access of freed memory)
fix wrong assertion fail when debug info contains more than one files
check returning line entry pointer is greater or equal to the first line entry pointer
add comment to mrb_assert in src/debug.c
Merge pull request #1496 from cremno/bug-debug-info-free

BUG: mrb_irep_free (access of freed memory)
Merge pull request #1497 from cremno/msvc-debug-info-feature

MSVC: compilation works again (+minor style fixes)
resolve conflict