Fixed naming inconsistencies with hoverdrive controller

I had originally written a pull request message but lost it so I'll keep this short.

The ```hoverdrive controller```'s name is not consistent across files and filenames. The appropriate spelling is "controller".

I've gone through and updated every file that contained the spelling error, which included the vmt, wtf, stool, and entity files. In particular, this renames the hoverdrive's class to ```gmod_wire_hoverdrivecontroller```   instead of ```gmod_wire_hoverdrivecontroler```.

I'll be honest in saying that I have not tested the changes, but this ```should```be all of the files that relate to the hoverdrive (at least according to N++).

If this pull request isn't accepted, I'd ask that an official patch is at least considered to address this issue. This is a minor problem so no biggie.

Thanks for reading.