Refactor and clean up the Nansat package

[akorosov]

Split up large functions into smaller parts.

DRY (Don't Repeat Yourself) KISS (Keep It Simple, Stupid)

Make sure we don't forget to make Nansat PEP8 compliant. That issue should come last before release in April 2015. PEP8 compliance for Nansat 1.0

[korvinos]

@akorosov transform_points method from the VRT class is not used anywhere in the VRT, but requested in the Domain. #check

[akorosov]

@mortenwh , can you review the VRT class?

[akorosov]

Remaining TODO for refactoring later. domain.py: 088 # TODO: logLevel pep8 229 # TODO: Test write_kml 283 # TODO: Test _get_border_kml 361 # TODO: kml_figurename can be not optional 365 # TODO: can we change that to max_min_lat_lon? 438 # TODO: Make DRY 687 # TODO: Bad names 754 # TODO: Review requested, falsification of negative value in resolution_y

nansat.py 217 # TODO: Fail tests with get item 298 # TODO: Test _fill_with_nan 400 # TODO: Test has_band # TODO: Discus change of band to band_name 487 # TODO: move to _set_new_extent 511 # TODO: Check how the get_GDALRasterBand method works with new VRT 640 # TODO: move the check to VRT.get_shifted_vrt 731 TODO: cross-check and update docstring and references/links 777 # TODO: move to _check_watermask_data 804 # TODO: # Move to Figure # Nansat inherits from Figure 976 #TODO: Move to Figure

nsr.py 73 # TODO: catch long in python 3

Also see 00612d4 for details.