Merge pull request FeatureBaseDB#509 from codysoyland/url-fix

Correct documentation link

turn on bitmapCache support in openCache()

cache performance enhancement

handle `unionArrayBitmap` width of bitmaps correctly

Refactor parser & AST to remove compile-time field names.

Consolidates all the pql.Call implementations into a single
pql.Call struct. This is needed to support user-defined schemas
on frames.

This also has the added benefit that a lot of redundant parsing
code has been consolidated.

Merge remote-tracking branch 'upstream/umbel-perf-improvements' into …

…umbel-perf-improvements

add docs about Benchmark Name field