Add file type and code fences support

[oblitum]

Also fix inconsistency on usage of global variables. See use of PATH vs path for example.

[dschrempf]

I did not check the code of this PR, but I wanted to state that in my opinion the file type and fences support is a very good idea! Before seeing this PR, I actually added an initialization script changing the major mode of my editor for the messages.txt file...