assets/gen-regions.js: Fix share URL prefix
gen-regions: Fix 'advanced' mode usage description
assets/gen-regions.js: Reduce grid labels size

Reduce the font size from 14px to 12px.
assets/gen-regions.js: Only submit form on enter

Don't keep submitting regions on every keystroke, that's just
obnoxious.
assets/gen-regions.js: Use GenRegions namespace
assets/gen-regions.js: Minor code style fixes
assets/gen-regions.js: Draw cells within borders

This prevents the 1 pixel overlap of cells outside of their borders.
assets/gen-regions.js: Don't draw out of range cells
gen-regions: Add a canvas tooltip

This contains a description of the currently visible region.
gen-regions: Change 'Share' button style to blue
assets/gen-regions.js: Don't encode the hash

...only decode the hash.
gen-regions: Reduce vertical register rows to 6
assets/gen-regions.js: Cleaner URL encoding

This escapes ampersand characters from the region string, preventing
parsing errors.
gen-regions: Update the `Sharing' documentation