Remove "legacy" proxy calls

[fluvf]

Based on #46

• Removes the ability to make crel.proxy.div() style calls
• Once again stores bound functions directly in the target function

Here pretty much just to show how much space the changes in #46 save, once the older .proxy style support is removed

[fluvf]

@KoryNunn can you give your opinion on this
I feel like this (and #46) would be useful changes, probably for a new major version, Assuming #21 isn't a problem anymore.
They simplify the API and code, and also add the features of #28