misc SlickGrid path column width etc. issues

[YairMarcowMavenomics]

A placeholder/umbrella for various low-priority issues:

• Path column isn't auto-sized
• Path column can be manually resized, but width isn't preserved as a property...
• ... even transiently to survive other property changes (which snap it back to default)
• Path column doesn't seem to support any other properties either...
• ... though r-click Edit Column Properties is enabled, but seems to bring up the dialog for whatever column was last updated.
• Path column probably oughtn't be Automatic-ally shown for non-ROLLUP queries (at least if/when we switch regular GROUP BY to the standard SQL flat results, without the "root" total)

[quigleyj-mavenomics]

Path col. auto-sizing is tracked more generally as a card on TBD: https://github.com/Mavenomics/MavenWorks/projects/1#card-28145376

Root totals on flat group tables was tracked on the old JIRA (JOVIAN-669) but wasn't migrated. Filed #50 to track that.