One more prerequisite step for Ubuntu
- python3 - numpy and pil
readme: added primecoin tip4commit button
doc: fixed reference to build dependency list
Merge pull request #91 from BugExplorer/Cyka

One more prerequisite step for Ubuntu
Merge branch 'master' of github.com:SFTtech/openage
doc: fixed typo in copying.md
Add .desktop file and placeholder icon.
Lowercase openage in .desktop.
Attempt at CMake file for icon.
Fix up cmake stuff with help from franciscod and convert to PIL.