First step in plot system conversion.
All references to "plotdef" changed to "cmtplot".
Fixed problem with double grid calls.
Change invalid "isfield" to "isprop".
Add set method for line smoothing; ensure lower case for string.
Methods now get settings from plotset.
Add "gridset" class.
Re-indent cmtplot file.
Grid argument processing uses "gridset" now.
Disk and external disk now use "gridset" for preference control.
Added "hasgrid" to external disk. Alphabetization.
Fixed poor choice of placement for grid plot argument call.
Plotting now seems to read the plotset/gridset things properly.
Update branch with master.
Fix old reference to `plotdef` in polygon.
Implemented separation of grid construction options and grid plot options.
Switched from clunky `pullGridArgs` to more general `separateArgs` scheme.
Took out unneeded extra conditional level in `set`.
Camel case changes for `gridArgs` and `closedcurveArgs`.
Merge pull request #31 from tobydriscoll/issues/#25-plotprefs

Addresses #25.