Initial commit of pipeline logic.

* timestream/manipulate/pipeline.py (ImagePipeline): New class holding
methods that initialize, run and print pipelines of computer vision
components.
(process): When run, this method goes through the totality of the pipeline.
(printCompList): Pretty prints the pipeline component information.

* timestream/manipulate/pipecomponents.py (PipeComponent): Parent class for
all pipeline components. Automatically inits the predefined variables
(__call__): Each pipeline component is a callable instance. When called, it
should execute the computer vision code.
(PCException, PCExBadRunExpects): Specific error classes for the pipeline
component exceptions.
(Tester): New pipeline component that can be used to test the ImagePipeline
class internals.
(ImageUndistorter): New pipeline component that should undistort image.
(ColorCardDetector): New pipeline components that should detect the position
of the color card.
(ImageColorCorrector): New pipeline component intended to correct the color
values in an image.
(TrayDetector): New pipeline component that detects the position of the tray
corners.
(PotDetector): New pipeline component that detects the position of the pot
corners.
(PlantExtractor): New pipeline component that should segment the plants.