Update OpenRA.nsi

fixed Error: unterminated string parsing line at OpenRA.nsi:144
ship license and changelog on all platforms

keep INSTALL & HACKING in the source code only
remove the tileset builder from core

not required anymore for d2k
it is also not shipped because it won't work standalone
fixed md5sum file not found global mix database.dat
simplify RPM buildpackage script for the build server

hard-code everything outside /usr/share/openra
silenced curl
cleaned packaging comments
Merge pull request #3959 from Mailaender/makefile

Removed TilesetBuilder from core
Merge pull request #3960 from Mailaender/rpm-revert

Simplified the RPM build scripts again
Merge pull request #3958 from Mailaender/docs

Ship COPYING and CHANGELOG on all platforms
Delete HACKING

unmaintained,
moved to https://github.com/OpenRA/OpenRA/wiki/Hacking