Add auto doxygen doc.

[CyberMango]

Add auto doxygen doc functionality. There are many old plugins for this.

[CyberMango]

Added for c/cpp/python files with doxygen syntax highlighting(for c/cpp only for now). For python files it is added with # comments instead of """ blocks, so a better plugin needs to be found.

works by standing on function name and running :Dox, or <leader>E .

Will add a better, more sophisticated plugin with jumps to the input locations, and with a shortcut of "/**" when i find one, like in vscode.