[[ ExternalsApiV5 ]] Engine-side changes for upcoming V5 Externals API - includes support code for Android externals.
Merge branch 'feature-externals_api_v5_engine' of https://github.com/runrevmark/livecode into feature-externals_api_v5_engine
Merge branch 'feature-externals_api_v5_engine' into release-6.1.1