Resolved issue 53
Implemented issue 43
Added regression test for issue 053.
Now ignores netcdf files created by test suite
Implemented issue 50, fully factored out format-independent behaviour so that grib and hdf open routines have same options as the old netcdf version.
Minor change in logic of TimeFormmater
Fixed missing import statement in modified openall and openmulti
Added in a tolerance autodetection for closeness of matches, based on spacing in axis
multiple_regress - code to do multiple linear regression
Fixed some bugs in generic open and save routines, added an optional opener function as an argument to openall
Fixed bugs related to constant in multiple_regress, and made output selection work more as one would expect.