add string constants
implement capwords
add string.printable
begin implementing operator module
implement operator.concat
implement sequenceSetItem and sequenceGetItem
implement sequenceGetCountOf and sequence operator methods
refactor new abstract sequence methods to be more like the existing ones (and remove the need for a string switch)
implement the abstract method sequenceGetIndexOf; implement operator.indexOf
implement abstract sequenceConcat
implement operator.neg
implement operator.pos; implement operator.xor; implement operator.rshift
implement remaining operator functions
add test for string module
add tests for operator module
fix some dist errors
remove some debugging statements
Merge pull request #179 from isaacdontjelindell/string-module

Implement string (partial) and operator modules
Merge pull request #1 from skulpt/master

update CS10 skulpt fork.