[linux] Update readme and build.sh script

* add dependency on python3-pip for uninstall
* move section on `make tmpinstall`

[Developer] Remove unused test window and related actions

[Android] Misc UI cleanup

Per PR comment, standardize keys to `ConfirmDialogFragment.` prefix

Fixes exception found while testing this scenario:
1. Emulator Android API 16
2. From globe button, add Afade (Latin) - SIL Cameroon QWERTY keyboard
3. From browser, install keyboard package from 
https://keyman.com/keyboard/sil_cameroon_qwerty
4.  Return to language picker, and add new keyboard
5. This triggers SimpleDateFormat()

Currently, the app name briefly flickers when ConfirmDIalogFragment finishes.

These changes make the flicker less noticeable:
* Set the app name blank in the Manifest
* Dismiss the dialog fragment and finish the activity

Also updated ConfirmDialogFragment to have a flexible message body (second parameter)

* And updated gitignore to ignore artifacts from Android Studio's "Layout Inspector" tool

[Android] Add HashMap.getOrDefault for older Android API levels

Add a LinearLayout view so text label goes to the right

[Android] Update installing a multilingual keyboard from local kmp package

Changed KeyboardListActivity so it passes a result (1) which will get the parent LanguageListActivity to finish too.

Addresses review comment

[Web] Beta versioning

Update to handle scenario when offline. 
* Use default set of options

When offline, only use languages info from kmp.json files.

Also cleaned up calls to setKeyboard

[common] bugfix for potential utf overrun on beta brach

The get/put routines now require the buffer size remaining to be read/written to permit checking and the iterator will update this value whenever iterator comparisions are made.  Other direct uses of get/put have been updated.

[Web] [Developer] displayUnderlying flag is now separate for different platforms.