git-progs-pk3packager.sh tool for distributing progs compiled from dev branches

This branch has no gamecode changes, only an utility tool script for distributing progs.

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#                                       #
#     Git progs pk3 packager script     #
#                                       #
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# This script compiles and packages progs into
# a pk3 which is meant to be distributable
# to players without compiling dev environments
# and allow them to host a listen or dedicated
# server with these progs.



# Please say to anyone who these progs are given to
# that they should not have multiple prog containing
# pk3s in their userfolder to avoid conflicts...



# Shipped files include:
#
# progs.dat for server VM.
# csprogs.dat for client VM.
# menu.dat for menu VM.
#
# progs-HASH.dat, csprogs-HASH.dat and progs.txt
#     for hosting a dedicated server
#     which uses these new progs and
#     hopefully sends this pk3 to clients.
#     These 3 files are all required
#     due to some builds having a named
#     progs-something.dat which server
#     could prefer over our unnamed progs.dat.
#
# changes.diff which tries to list all code changes
#     since common ancestor with master branch.
#
# All .cfg files which have been edited
#     since the last stable release.



# The pk3 is moved to Downloads directory for easy
#     sharing and house keeping. If the user has set
#     their xdg directories' DOWNLOAD dir then it'll
#     be respected. Second option is ~/Downloads
#     directory. If neither of those exists then
#     it's left in the script's current working
#     directory, the root of xonotic-data.pk3dir