android: Install p4a using pip
Add 'set -e' to sh scripts, they must stop upon any error
README.md: kivy does not specifically require python2
android: Overhaul initialization scripts
android: Simplify apk build scripts by using the 'common' file
Merge the scripts cardconv and cardsetsgiftobmp
android: Fix startup script shebang to python3
android: Simplify mkkeystore and ignore the keystore file
android: Fix up debian prerequisites
The package cython (as opposed to cython3) even caused me to produce
an apk that did not start (TypeError: must be str, not bytes).
Android SDK requires java8; install and set as the default.
The build processes complained about lld and libtinfo5; added in.
mercurial (or hg) is seemingly unused.
The pip pcakges were needed by android/initsdk.py which is gone.
android: Ensure that the html files are built
