linear mask retention

unit test

review changes

review changes

review changes

new init

license header
Updated to latests cartopy.
float64 reg coord if needed

restored pp_netcdf tests

test revert

test refactor

comment tidy
Refer travis to specific cartopy SHA.
Cartopy version dependency in INSTALL updated
Merge pull request #947 from dkillick/update_INSTALL_doc

Cartopy version dependency in INSTALL doc updated
Merge pull request #944 from pp-mo/cartopy_v10_candidate

Cartopy v10 candidate
Merge pull request #919 from marqh/maskLinearInterp

linear mask retention
ppsave test

pep8
Merge pull request #943 from marqh/testPPSave

ppsave test
Iris v1.6 whatsnew.
Merge pull request #917 from bjlittle/whats_new_1p6

Iris release v1.6 whatsnew.
Fixed issue with derived_phenomena example expecting colorbar object to
be a tuple.
Merge pull request #952 from esc24/derived_phenom_example_mpl131_support

Fixed mpl 1.3.1 issue with derived_phenomena example
Merge pull request #928 from marqh/hires_reg_coord

float64 reg coord if needed
Changed coord_dims to accept a coord name as well as a coord
added name_or_coord kwarg to iris.cube.Cube.coords
removed more uses of coord and name kwargs
removed redundant code in coord_dims
Fixed reliance on old coord_dims behaviour in calculus