is.equal, is.array, is.number, is.dictionary, is.string helpers
Iterator helper class
functions from op namespace
functions from op.attributes namespace
Delta constructor
Delta.push() implementation
Delta.chop() implementation
Delta.compose() implementation
Convert only string inserts to unicode in Delta constructor

Inserts may have also numeric values (representing non-textual media)
let constructor's param be another Delta object
Delta.insert() implementation
attributes as dict's key, not attribute in Delta's constructor
Delta.length() implementation
Delta.delete() implementation
Delta.retain() implementation
Delta.slice() implementation
Import missing imports :)
Two lines fixed

Iterator is the only class imported from iterator module (not from op module)
Standalone functions
LICENCE removed as for this moment I have no idea under which licence it should be distributed