can mark an int or float as not being allowed to be higher than some bound
examples for NotMoreThan attribute
NotLessThan attribute and drawer
added NotLessThan examples
better error handling if lower bound type is mismatched to property
better error reporting of mismatched types in NotMoreThan
fix typo in NotLessThanDrawer
added readme for single bounds
Merge pull request #3 from tenpn/singlebound

yay :+1: