Rename and cleanup

[gbrener]

This PR is a continuation of @DavidMertz's work on splitting off TextAdapter from IOPro. With this PR merged in, the project should be buildable (with all tests passing) for both Python 2.7 and Python 3.5 on Ubuntu 16.

A few key differences:

• "TextAdapter" package is now called "textadapter"
• Cython code for the core TextAdapter low-level data structures is in a directory called "core"
• README now includes instructions on how to build, install, and test
• All files not related to TextAdapter are gone. There may still be some dead code, but this can be removed in a future PR
• Dynamic loading of modules/classes/functions in __init__.py is replaced with static loading
• Due to shared library issues with a couple of conda packages, versions of the pcre and zlib conda packages are pinned in the meta.yaml