Remove origImg

* scripts/run-pipeline.py (img): We don't need origImg given that we pass a
TimeStreamImgage throughout the pipeline.
Refactor derandomization

Handling everything on a single table made the code too complex and error prone.
We now handle three tables: (i) a time stream table, (ii) a csv table and (iii)
a master table.
* util/derandui.py: Refactor in order to use three tables instead of one.
* util/derandui.ui: Likewise.
Use closest existing timestamp

* timestream/manipulate/pipecomponents.py (DerandomizeTimeStreams.refreshMids):
Subject
Add ability to see derandomized image.

* util/derandui.py (DerandomizeGui._showPrev): New method to show a preview of
the derandomization.
(PanZoomGraphicsView): Activate this class so we can pan and zoom the preview
image.
Allow netcdf4 versions equal or greter than 1.1.0

* setup.py (install_requires): Subject
Require absolute paths in TimeStream.

* timestream/__init__.py (TimeStream.{path,create}): We only accept absolute paths. The
change from relative to absolute should be done in the user interface code.
Fix test of ts creation WRT relative paths

fb36730 requires that all paths are absolute, and the test had a
relative path in it. I fixed that, and added a test for relative paths.
Relegate netcdf to ./scripts/timestream2netcdf.py
Add script to just run the tests, skipping flake8
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
Install freeimage dev package in travis CI
Rewrite read_image and add tests
Replace all X.imread calls with read_image

read_image (from timestream.parse) is a wrapper around scikit image's
imread using freeimage. This change allows us to use a single image
reading function to avoid weird bugs where we have several image reading
functions at once. This also allows us to change our mind as to which
image IO library to use and only need to change one function.

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