Add CMake to compile for linux

* Fixes to compile with wxWidgets 3.0
* Fixes to compile in linux 64 bits
* Update linux instructions in README
* Remove source/Makefile
Merge pull request #6 from edubart/master

Add CMake to compile for linux
Lots of changes

Removed libxml2 to use pugixml.
Fixed a bug with the progress bar.
Changed some things in most xml files that pugixml did not like.
Updated the Visual Studio project.
Any NULL symbol has been changed to nullptr.
This most probably broke the CMake that was recently added.
And probably some other things.
Remove DLL.
Lets not use the .otgz format yet.
Forgot this
Update CMake and README
Merge pull request #11 from edubart/patch-cmake

Update CMake and README
Bug fix

sizeof(std::string) can be 4 or lower so lets do this instead of a
static assertion.
Fix
Missed this.
Cleaned up README some.
Revert "Lets not use the .otgz format yet."

I want to be able to open my maps... No reason to disable this, make a precompiler
directive to disable perhaps.

This reverts commit 241f8c9a23475b11abb885634ec9648750b3eb4b.
Fix warnings, fix archieve compilation error
Remove all warnings
Merge pull request #16 from Baxnie/master

Fix warnings, fix archieve compilation error
Run using working directory, remove unecessary ;
Merge pull request #17 from Baxnie/master

Run using working directory, remove unecessary ;
Make able to run from linux build directories

* Remove annoying std::cout
* Update linux README instructions
Fix crash when loading extensions.