Deprecate the following obsolete functions and properties:
* `keyman.helpURL`
* `keyman.util.rgba`
* `keyman.util.toFloat`
* `keyman.util.toNumber`
* `keyman.util.toNzString`
Use correct language for code blocks in Keyman Engine for Web
documentation.
Test-bot: skip
The `loaduserinterface` and `unloaduserinterface` events were
incompletely implemented, and the documentation was incomplete. This
change:
1. ensures `loaduserinterface` is called any time a UI is set, either
during initialization or when the property is set later.
2. ensures `unloaduserinterface` is called immediately before a UI is
shutdown.
3. updates documentation
4. removes misleading commented code in kmwuifloat.ts
Test-bot: skip
Note: build.sh updated to make sure that test:help build action:target
doesn't also call test.sh by adding `:_all` meta-target.
Note: CI will need a new help-keyman-com.sh build step to deploy web
engine help.
Fixes: #12347
