new cell cmp
preferred logic
contig handling
grib1 unit 10 handling
tidy up
Merge pull request #171 from bblay/grib1unit10

GRIB1 time-unit 10 handling
Remove redundant and erroneous standard_name to LBFC/STASH PP save
rules.
Reinstate PP save rules to set LBFC only.
Merge pull request #190 from bjlittle/redundant_pp_save_rules

Remove erroneous standard_name to STASH PP save rules.
Add CONTRIBUTING.md

Fixes #100.
Merge pull request #195 from rhattersley/contributing

Add CONTRIBUTING.md
Move cell tests into a separate file and add some new tests.
review actions
Merge pull request #121 from bblay/cellcomp

new cell comparison
added tests for GRIB ProductDefinition 4.9 and to fail unrecognised PDTs
tidied new tests and revised for different proposed solution
added partial support for GRIB2 PDT4.9 ; tidied test_grib_load
fix test comment in test_grib_load
Add fake travis configuration
Update test results to use relevant Cartopy