Spelling corrections

Basically correcting all instances of the expression "bellow", replacing
them with "below"
Merge pull request #3 from caparicajr/master

Grammar Nazi arrives! Basically correcting all instances of the expression 'bellow', replacing
them with 'below'
Change 'geophysical' for 'geophysics'. Better for search
Removed unused deprecated matplotlib import nxutils
Merge branch 'master' into devel