Set body+ext together with filename, get long extension, get/manipulate path parts

->filename() - set filename (will populate body and ext)
->extLong - get compound extension (.ext.extra)
->pathParts() - get or manipulate path parts

1.2.0: ->reset(): added reset to avoid reinstancing object

->filename: accessor for easier filebody+ext access
getParts(): explode helper func to get back all file parts in an array
extended tests to check for filename property helper values
added some extra test cases related to file extension with dot (if ext is nonexistent, it won't add a dot into the resulting string)

1.1.0

Dots can now be used when setting extension with ext()

First release

1.0.0

Update README.md