Switch to using G_DISCARD for call_pv

PUTBACK was being called even for the error path which didn't use the
stack. Emitting the "script error" signal can involve running Perl code
(Irssi:core::destroy) therefore the stack can be reallocated. This
can result in the perl stack being corrupted because the local stack
pointer is out of date (although as it's use of freed memory the crash
is not always instant).
Correct use of perl stack macros

Further to pull #49 this is the result of an audit of the use of perl
stack macros. There were several cases where PUTBACK was being called
where the stack pointer could be out-of-date.

Also some misc. cleanup where the macros were used needlessly.
Use PREFIX from 005 to decide if a nick flag is of op level

Fixes #61.
add print_text_after_time to specify time stamp for lines
add signal for line removal from textbuffer
Merge pull request #68 from falconindy/master

Autotools cleanup
Merge pull request #49 from dgl/stackem

Move PUTBACK to within the scope which uses the stack
Merge pull request #52 from dgl/stack-cleanup

Correct use of perl stack macros
Merge pull request #62 from dgl/prefix-nick-flags

Use PREFIX from 005 to decide if a nick flag is of op level
Update crash.txt to point at github
Merge pull request #69 from dgl/crash.txt

Update crash.txt to point at github
Merge pull request #11 from ailin-nemui/print_text_after_time-api

add print_text_after_time to specify time stamp for lines
Remove superfluous entry from EXTRA_DIST

curses.m4 is already included by automake as it's an m4 depdendency.