Remove useless include.
Remove checking of unused headers and functions.

This speeds up the configure stage a little bit.
Restore help files to being part of the source distribution.

Ensure it works with make distcheck
Fix potential unnecessary exit in trying to handle spawning of external command.

Mostly only a problem on Windows if the gspawn-win32-helper.exe program is not available.
NB Currently we package it in the Windows installation.
Need more files for Windows packaging.

Put locale files in right place.
Add our text files and COPYING notices.
Setup to package GTK2.24.10
When creating via Wine - ensure production of items not known how on Windows:
. ChangeLog.txt
. Help PDF
. configure script

Need to use xsltproc to complete build cleanly.
Fix crash when cancelling an 'Acquire' in progress thread task.

Issue caused by SHA:b2aa700f11bb54b6f9c6a0f8cf95bf3caccf7df5 in supporting a non thread method
Need to free memory at the correct time and place.