fix(ios): use CFBundleShortVersionString for version

chore(mac): Update whatsnew for 15.0

fix(developer): handle exception on unpaired surrogate

chore(ios): Document minimum iOS version 12.1

feat(ios): testflight builds for PRs

Fixes #6480.

fix(iOS): check version during package install

auto: increment beta version to 15.0.229

package install fails with alert if Keyman version in use is lower than the minimum specified in the package

fix(mac): check package fileVersion during install

feat(web): prediction casing follows current layer

auto: increment beta version to 15.0.228

docs(linux): Update testing section in readme

feat(developer): check for duplicate store/group names

fix(developer): validate kmconvert parameters

fix(developer): icon editor font color now follows fgcolor

feat(developer): add Clear All button to icon editor

feat(developer): check filename case consistency when compiling keyboard

feat(developer): hint on unreachable code

fix(web): rely on caller for unmatched keys

chore(common): Update in-app help versions to 15.0

chore(android): Document minimum required version of Chrome