Add some more diagnostic warnings

[MCMrARM]

We should show a warning when the launcher would use software rendering (llvmpipe). This could be achieved by parsing the output of mcpelauncher-client -v, which looks like the following:

mcpelauncher-client 145d215 / manifest b016744
CPU: GenuineIntel Intel(R) Core(TM) i7-8700K CPU @ 3.70GHz
SSSE3 support: YES
GL Vendor: nouveau
GL Renderer: NV120
GL Version: OpenGL ES 3.2 Mesa 18.2.4

and checking whether the GL Version string contains llvmpipe or not. Except for the first line, the output will be expected to be in the form of Key: Value. User should be linked to a wiki page (that should be created) where he can find how to properly install the driver for their system.
Additionally, a warning should be shown when SSSE3 support is NO. User should also be linked to a wiki page explaining why this is a problem.

In both cases a [Do not show again] checkbox should exist.

[MCMrARM]

This has been largely implemented.