added a public isLevel method that can be called on a subclass of MCLevel that has one of the appropriate methods.
added a public isLevel method that can be called on a subclass of MCLevel that has one of the appropriate methods.

For example, MCInfdevOldLevel.isLevel("World4") will return True if World4 can be loaded using MCInfdevOldLevel("World4")

codewarrior0/pymclevel,mcedit/pymclevel,mcedit/pymclevel,arruda/pymclevel,codewarrior0/pymclevel,ahh2131/mchisel,arruda/pymclevel,ahh2131/mchisel