ggplot2 added as depends instead of suggests

so dependency is automatically installed
generic dual inlet implementation

should allow reading of many dual inlet (.did) files regardless of how
many cycles and masses are measured
uml structure updated for dual inlet

includes structural updates to isoread that came with the dual inlet
upgrade
dual inlet support - tests

testthat tests for dual inlet support
update read me for dual inlet
docu updated

documnetation updated