Making circuitscape a python package

This will convert `circuitscape` to a python package, that can be registered at `pypi` and installed with `pip`.

Please do not merge this yet.

Though the packaged version of `circuitscape` works fine as a regular python package, I am not able to get it to work as a mac app bundle. I shall try to find out a fix. In the meantime, please give this a try on your machine.

Update:
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The mac app bundle works now.

Here's a brief of the updates included in this:
- Sources for circuitscape python package are under `circuitscape` folder.
- Files for the verify routines are under `circuitscape/verify` for now, though they can be moved out later.
- There is a new `bin` folder that contains wrapper python scripts for invoking the app in console mode (`csrun.py`), gui mode (`csgui.py`), running verify(`csverify.py`).
- New makefile targets for python packaging: creating package (`pypi`), registering with pypi (`pypi_register`, to be done only once) and updating releases (`pypi_upload`, to be done after creating the package)

Apart from this, some files have been renamed and merged.