CMake Migration

Created by: awakecoding

Migration of the build system to cmake.

I have tried my best to replicate what the original build system was doing with cmake. It should be able to provide configurable builds, with proper installation of data files and translations.

The only little glitch left which I am not sure of is building remmina with libssh. The NX plugin can build and load fine with it, but as soon as remmina is built with libssh it will fail to start with an error saying that remmina is linked to both GTK2 and GTK3 libraries at the same time. When trying to identify the culprit I noticed that when libssh was enabled, remmina was linked against libgtk-x11-2.0.so.0, while it wouldn't if libssh was disabled.

The other thing which would be left to check is how to create packages, but that can come later.

If the current cmake migration is stable enough to be merged without affecting too much people, I suggest we go ahead.