Removed __repr__ definitions in rhythmmakertools.
Removed __repr__ definitions from sievetools.
Removed custom __repr__ definitions from CyclicList and CyclicTuple.
Added `keywords_ignored_when_false` keyword to StorageFormatSpecification.

Keywords included in this list, where bool(value) evaluates to false will be
stripped from the repr or storage format.

This helps us ignore empty iterables and None.
Improved __repr__ output of StorageFormatManager.
Removed __repr__ definitions in indicatortools.
Removed more __repr__ definitions.
Merged master.