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pointer is out of date (although as it's use of freed memory the crash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where the stack pointer could be out-of-date.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.
rename configure.in -> configure.ac

Silences warning on newer autoconf:

aclocal: warning: autoconf input should be named 'configure.ac', not
'configure.in'
add AC_CONFIG_MACRO_DIR([m4]), move *.m4 files to m4/

Silences notice on newer autoconf:

libtoolize: Consider adding `AC_CONFIG_MACRO_DIR([m4])' to configure.ac and
libtoolize: rerunning libtoolize, to keep the correct libtool macros in-tree.

This helps keep the top-level build directory clean, too
s/INCLUDES/AM_CPPFLAGS/g

Silences warnings on recent automake such as:

src/core/Makefile.am:3: warning: 'INCLUDES' is the old name for
'AM_CPPFLAGS' (or '*_CPPFLAGS')
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
Initial implementation of 256 colour support for Irssi

This patch implements some 256 colour support for Irssi up from the
previous 16 colours. Initial parsing of the %x/%X format codes is
implemented and the parser accounts in advances the char* for
that.

The colour attributes are widened from 4 to 8 bit. The colour protocol
is changed to a new format. Some pointers to remaining work are
written in the comment in textbuffer.h.

Note that Irssi already does support requesting 256 colours from the
terminal in the original source code, so this part did not have to be
touched.
Finish 256 colour support for Irssi

256 colour patch is cleaned up and the remaining cases are made work,
this includes especially Theme support, which was not implemented
before. Changes not related to colours were reverted again, making a
review of the two patches against master easier to follow.

As a byproduct of the Hex-colour code parser, the 24bit colours are
also implemented. Actually using them in the terminal is guarded by a
compile time switch (as well as a run time switch), as it breaks the
existing colour protocol and requires additional storage.

To make a seamless usage, down-conversion is provided for 8 and 16
colours.

Diverging from Tom's approach, the colour protocol is reverted back to
the original one. Unfortunately, the changes required in the Theme
engine will break the API.

For more details, please refer to the patch documentation at either
http://irssi-docs.wikispaces.com/Notes-256-Colour or
https://github.com/shabble/irssi-docs/wiki/Notes-256-Colour