Euclid reorg

[eahanson]

I'm thinking of updating Euclid with some of the code that we've written over the past 6ish months. I'd also like to reorganize the code a bit.

My proposal:

• remove the intermediate Extra module which seems unnecessary since almost all the modules are children of it. Usage will be nicer: Euclid.String.foo() instead of Euclid.Extra.String.foo()
• maybe move some functions to other modules as needed
• add typespecs
• add module docs and function docs

I'm thinking of doing an intermediate 0.2.5 release with everything moved around and the old code still in place but deprecated, and then immediately a 1.0 release with the deprecated versions gone and typespecs and docs added, and then future 1.x releases with new code from our recent work.

Objections/comments?

[sax]

This seems like a great way to make this change. It might help to add a brief "Upgrading to 1.0" section to the readme or docs, which basically just says to update to 0.2.5 and fix deprecation warnings before updating to 1.0.0.