Adds import support for fitting window copy. Resolves #91

This requires us to pass an active fit to use as a base for the modules, as the format does not include ship information. Features:
* If active fit has modules, makes a new fit using same ship
* Does basic dummy checking. As the format doesn't include ship info, it will probably be common for someone to accidentally try to import a Legion fit to a Rifter by mistake. Import logic checks module legality for fit and, if fails, silently halts import without saving.
Fixes refresh issue with importing from fitting window into empty fit.

This removes a conditional that makes sure we don't fire the FitSelected event if the active fit is same as imported fit. Removing this, to my knowledge, has no adverse effects because when importing we *always* create a new fit (with the exception of the new fitting window import) and thus this conditional is not needed.