Updated license verbiage in source code per #543.
Merge pull request #560 from csimons/master

Updated license verbiage in source code per #543.
Spelling fix ('suble' -> 'subtle').
Spelling fix ('simmultaneously' -> 'simultaneously').
Spelling fix ('seperated' -> 'separated').
Spelling fix ('moodify' -> 'modify').
Spelling fix ('formating' -> 'formatting').
Spelling fix ('artifically' -> 'artificially').
Spelling fix ('detla' -> 'delta').
Spelling fix ("dont" -> "don't").
Spelling fix ('Monaday' -> 'Monday').
Spelling fix ('thursday' -> 'Thursday').
Spelling fix ('sould' -> 'should').
Spelling fix ('wieght' -> 'weight').
Spelling fix ('wieghted' -> 'weighted').
Spelling fix ('Lightwieght' -> 'Lightweight').
Spelling fix ('initiall' -> 'initially').
Spelling fix ('udpated' -> 'updated').
Spelling fix ('tranpose' -> 'transpose').
Spelling fix ('catergory' -> 'category').