Make the cmap accurate.

Regenerate the fonts with on-char-per-segment to support an accurate cmap.

Other changes include:
Move several routines from IncrementalFontUtils to IncrementalFont to make them object member functions.
make a bmp and smp version of the NotoSansJP-thin demo

Add debugging support to check for unresolved promises that linger.
Add FontInfo class to formalize the API.
Add a CharCmapInfo class to make glyph Ids to chars.
Add a mechanism to have an alternate server.
Handle missing data more consistently.
Clean up demo pages.
Move debug variables out of global space and into a subroutine.
Fix the mutation observer code to recurse thru trees.
Fix a bug where a set of fonts would not update if any did not update.
Pass in positioning info into the demo code.