* Use Clang instead of GCC (deprecated)
* Raised/added minimum Android API version (16)
* Use (static) libc++ by default/explicitly (gnustl and stlport are deprecated)
* Add verbose flag to toolchain builder where missing
* Make build scripts fully whitespace safe to the extend premitted by autotools
* Let all build scripts fail fast on error, previously they would continue and then fail with spurious follow-up errors burrowing the actual issue
* Ensure that all build scripts start with a valid shebang (`#!`)
* Fix jumbled letters in `android/build_build_app_x86.sh`