Merge branch 'release-branch-v4.0.2' into 'master'

Release 4.0

See merge request ws/client/androidapp!440

added changelog.

remove unused planning doc.

update wsnet.

update release info.

fix build script.

show message for unavailable feature.

Merge branch '3.91' into 'develop'

updated to v3.91

See merge request ws/client/androidapp!332

Merge branch 'fix_gesture_back_button' into 'develop'

enabled predictive back gesture

See merge request ws/client/androidapp!331

updated version info.