Fix grammar mistakes in comments of int_stack.h
Add int_stack_clear() function

Removes all element from the stack.
Add commands_block_finished() function to commands

An event like function, which should be used to inform commands
unit that set of a command has come to its end.  Allows for
performing some of internal checks.
Use copy_str() instead of strncpy() in config.c
Display error on missing :endif in sourced file

Thanks to filterfalse.
Merge branch 'error-on-endif-lack'

Display error after sourcing file with unmatched :if/:endif
statements.

Thanks to filterfalse.