Previously, bool2str() accepted a broad array of boolean values and
bare strings, without any attempt to validate that the strings in any
way resembled "true" or "false" (or any of the other values bool2num()
accepts). This commit narrows the input confinement to TrueClass and
FalseClass, which means that bool2str() will only interpolate
strict boolean values now.
Python likes to have its constants Capitalized, and the capitalize
function only understands strings... so I shave a yak.
bool2str will convert a boolean to its equivalent string value,
and camelcase extends on uppercase & downcase to convert an underscore
delimited string into a camelcased string.
