Make DetectCollision use size params

step 1: b and c are divided by 2, and then used to find the center of
each object (horizontal only)
Make DetectCollision use size params.

Part II - now the horizontal check is made solely with size values
passed in b and c
Make DetectCollision use size params.

100% relying on box sizes passed in B and C. Tested, seems to be
working...
Add comments to DetectCollision
Apply a DRY refactor to DetectCollision
Change parameters for DetectCollision

Now it is HL = Obj1X, Obj2X
DE = Obj1Y, Obj2Y
>> each reg. pair tests an axis
Document improved DetectCollision
Add more documentation to DetectCollision
Implement DetectCollision in thug module
Add a fix for thug/sword coll. detect

When the player is facing left when attacking, the x-axis parameter must
be adjusted (+4) before collision detection, because the sword is only 4
pixels wide (and not centered in the tile)