increase precision of git ignore; ignore autotools compile script
configure.ac: add x11 to GUILIBS (Closes: #555882)
configure.ac: update

follow automake's instructions:

src/Makefile.am:27: compiling `padevchooser.c' with per-target flags requires `AM_PROG_CC_C_O' in `configure.ac'

autoupdate says AC_TYPE_SIGNAL in configure.ac is obsolete
src/padevchooser.desktop: remove encoding key

remove obsolete encoding key line from desktop file, per lintian