Update internal class names to match the GUI names

[apocalyptech]

The most egregious and confusing example right now is what's called "Objects" in both the GUI and the documentation is internally referred to as "mapscripts," a holdover from my very first draft of that class when I wasn't 100% sure exactly how those bits of data should be classified. This in particular gets extremely confusing when we start talking about actual scripts, which are just bits of text attached to various things. At any rate, the code should really get updated at some point to be far more unambiguous. Doing so will almost certainly involve a pretty major QA effort.

Before actually doing work on that, though, we might want to actually just sync everything up to what BW calls all these various things, since that way we'd be consistent with the actual engine code itself.

This is all something for a later release, of course.

[apocalyptech]

Another change I've wanted to do for some time: rename our internal "Square" class to "Tile" instead.

[apocalyptech]

A brief note to myself so I don't forget: constantsbN.scriptflags will need updating.

[apocalyptech]

Okay, this should be mostly good to go now. Any future renaming which we do for consistency's sake should hopefully be on a much smaller level, so I'm okay with closing this out for now.

A summary of the main changes which I did:

• Square -> Tile \ Various variables used "sq" as their name, those were changed to "tile"
• Mapscript -> Tilecontent * This was the major work, by far, since so much of the existing code ended up referring to these as just plain "scripts." * Various functions likse "addscript" and "delscript" got renamed in addition to the objects. * A "scriptid" field existed in Tile * In the constants files, objecttypetable -> tilecontenttypetable \ Various GUI elements and event names were updated to change "script" to "tilecontent" as well

Most of the rest of the work to bring the variable names up-to-date with the docs from BW was done by Elliot.

So anyway, I'd consider this done enough to close. So, closing!