Lua skin additions

[asmagill]

Some proposed changes to LuaSkin:

I know we're planning a move to Swift soon, but in the meantime, this pull has the following:

1) the pushNSObject: methods will now check for a more specific match (i.e. isMemberOfClass:) and then fall back to isKindOfClass:.

2) the log*: methods will now accept varagrs in the NSString stringWithFormat: style.

• this allows [LuaSkin logError:@"%s - callback error", USERDATA_TAG], as opposed to the current [LuaSkin logError:[NSString stringWithFormat:@"%s - callback error", USERDATA_TAG]]

[cmsj]

Assuming CI "passes" with only its regular amount of failing tests, this lgtm.

[codecov[bot]]

Codecov Report

Attention: Patch coverage is 94.20290% with 4 lines in your changes missing coverage. Please review.

Project coverage is 27.95%. Comparing base (ec9a8ea) to head (e86ba5c).

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #3667 +/- ## ========================================== + Coverage 27.65% 27.95% +0.29% ========================================== Files 191 191 Lines 43472 43528 +56 ========================================== + Hits 12023 12167 +144 + Misses 31449 31361 -88 ```

[cmsj]

The regular amount of tests failed, so I'm merging this.

[asmagill]

Was just about to add comments in the internal pushNSNumber: method for when we migrate to Swift.

We currently do a ptr comparison against kCFBooleanTrue and kCFBooleanFalse to determine if an NSNumber is boolean (@encode for BOOL is the same as for unsigned char, so we can't use that).

Per https://stackoverflow.com/a/30223989, it's probably safer (and Swift friendly) to do something like:

func isBoolNumber(num:NSNumber) -> Bool
{
    let boolID = CFBooleanGetTypeID() // the type ID of CFBoolean
    let numID = CFGetTypeID(num) // the type ID of num
    return numID == boolID
}

They give an Obj-C version as well, but I don't want to change what's currently working atm.

If we have a place where we're sticking Swift related notes, let me know and I'll post this there.

[cmsj]

We don't have such a thing yet, but we probably should. I wonder if a Project might make sense?