Adapted to avoid Matlab Mapping Toolbox

Function can now be used without access to the Matlab mapping toolbox.
Extracts sigma layers from POLCOMS output

Extracts sigma layers and bathymetry from NOCL operational surge model
(POLCOMS).
Minor edits to remove old comments
Fixed bugs affecting orientation of output

Fixed bug which rotated (E-W becomes N-S) inputs, generating incorrect
outputs. Also incorporated PWC's bugfixes for his parent
'get_POLCOMS_tsobc.m' script.
Fixed rounding errors in Itime2 outputs
Minor edit to parameterise inputs
Merge remote-tracking branch 'upstream/master' into dev
Added documentation and author history to file
Merge pull request #2 from kjamoudry/dev

Merge fixes from Karen Amoudry to correct some rounding errors in the Times and Itime2 variables in the forcing files. These changes are going to my dev branch (the changes have also been applied to the master branch).

In particular, there are significant changes to the greg2mjulian (and mjulian2greg?) function to use native MATLAB functions (datenum et al.) rather than the MATLAB Central third-party greg2julian function. 

This also includes some changes which I (Pierre Cazenave) made to the code in parallel to Karen's changes (though on different functions).