Document windows installation

* doc/index.rst: Add a new section called "Getting Started"
* doc/starting.rst: Document Windows installation process.
Deal with errors in pipecomponents with exceptions

* timestream/manipulate/pipecomponents.py (ColorCardDetector.__exec__): Raise an
exception when we cannot find color card.
Switch to using scikit image as primary IO lib

Now, we prefer scikit image as the image IO library, as it is
pip install-able and doesn't reverse the colours.

Also some formatting changes throughout, none of which afffect acutal
code.

Changes to be committed:
      modified:   timestream/__init__.py
      modified:   timestream/manipulate/__init__.py
      modified:   timestream/parse/__init__.py