Apk build scripts

- updated for use with p4a version 2019.10.6.
- additions to build instructions.

README.android

@@ -1,6 +1,9 @@
 
 Prerequisites (needs root):
 
+  (For updated information on these subjects please consult the scripts in
+  android/debian).
+
   On a 'freshly installed' Ubuntu 16.04 (32bit), the following
   additional packages had to be installed:
 

android/debian/apt-installs.sh

@@ -18,3 +18,17 @@ apt-get install -y \
   lld
 
 update-alternatives --set java /usr/lib/jvm/java-8-openjdk-amd64/jre/bin/java
+
+apt-get install -y --no-install-recommends \
+  imagemagick \
+  python3-tk \
+  ccache \
+  libltdl-dev
+ 
+# set python3 as default.
+# make python alternatives selectable.
+# (debian stretch, adapt for different versions)
+
+update-alternatives --install /usr/bin/python python /usr/bin/python2.7 1
+update-alternatives --install /usr/bin/python python /usr/bin/python3.5 2
+

android/initsdk

@@ -12,7 +12,7 @@ fi
 
 urlbase=https://dl.google.com/android/repository/
 tools_zip=sdk-tools-linux-4333796.zip
-ndk_zip=android-ndk-r17c-linux-x86_64.zip
+ndk_zip=android-ndk-${ndkver}-linux-x86_64.zip
 
 mkdir -p $sdkdir $ndkdir
 

android/mkp4a.common

@@ -8,8 +8,11 @@ tmpdir=${HOME}/.cache/tmp-for-p4a/pysolfc/src
 cardsets_dir='PySolFC-Cardsets--Minimal-2.0.1'
 cardsets_file="${cardsets_dir}.tar.xz"
 
+p4aver="2019.10.6"
+ndkver="r19c"
+
 sdkdir="${HOME}/.cache/sdk-for-p4a/sdk"
-ndkdir="${HOME}/.cache/sdk-for-p4a/android-ndk-r17c"
+ndkdir="${HOME}/.cache/sdk-for-p4a/android-ndk-${ndkver}"
 pkgdir="${HOME}/.local/share/python-for-android/packages"
 
 # gradle may need this.

android/mkp4a.init

@@ -17,10 +17,10 @@ echo '### install p4a'
 
 if [[ $# == 0 ]]
 then
-    if not python3 -m pip install -q --user python-for-android
+    if not python3 -m pip install -q --user "python-for-android==${p4aver}"
     then
         echo "obviously inside a virtualenv, so omit --user"
-        if python3 -m pip install -q python-for-android
+        if python3 -m pip install -q "python-for-android==${p4aver}"
         then
             echo "done"
         fi