Allow Linux users to build Android even if Python 2 is their default Python

After this commit, users who have the `python` executable as Python 2 can do simply:

    cd android/
    ./build-all.py
    ./build.py

Previously, the following would fail:

    python3 build-all.py

since build-all.py did subcalls to `python build.py`.

Remove install-all.py as it is redundant with `build-all.py -deploy`,
instead of fixing it as well.

Introduce argparse since we are separating argument parsing out of
the `main()` function.

Tested in Ubuntu 16.04, behaviour should be unchanged for Windows.

android/build-all.py

@@ -1,8 +1,11 @@
-# Build all examples
-# Pass -deploy to also install on connected device
+#!/usr/bin/env python3
+
+import argparse
 import subprocess
 import sys
 
+import build
+
 EXAMPLES = [
     "bloom",
     "computecullandlod",
@@ -64,18 +67,16 @@ COLOR_END = '\033[0m'
 
 CURR_INDEX = 0
 
-BUILD_ARGUMENTS = ""
-for arg in sys.argv[1:]:
-    if arg == "-deploy":
-        BUILD_ARGUMENTS += "-deploy"
-    if arg == "-validation":
-        BUILD_ARGUMENTS += "-validation"
+parser = argparse.ArgumentParser()
+parser.add_argument('-deploy', default=False, action='store_true', help="install examples on device")
+parser.add_argument('-validation', default=False, action='store_true')
+args = parser.parse_args()
 
 print("Building all examples...")
 
 for example in EXAMPLES:
     print(COLOR_GREEN + "Building %s (%d/%d)" % (example, CURR_INDEX, len(EXAMPLES)) + COLOR_END)
-    if subprocess.call(("python build.py %s %s" % (example, BUILD_ARGUMENTS)).split(' ')) != 0:
+    if not build.main(example, args.deploy, args.validation):
         print("Error during build process for %s" % example)
         sys.exit(-1)
     CURR_INDEX += 1