Add error-polymorphic versions of dynamics primitive parsing functions.
Add error-polymorphic versions of dynamics primitive parsing functions.

When writing `parseProperty("foo", parseString, someFunction)`
it's often the case that you don't want to use 'identity' for
someFunction, but the current design allows only 'identity' in
this situation.

0b1kn00b/thx.core,fponticelli/thx.core,andywhite37/thx.core