iOS; fix project template for ldflags breaking the builds
iOS; fix compiling against ARC
ignore; iOS projects for now
input; Add support for keyboard based input (soft keyboard on mobile IME on desktop etc)

see https://wiki.libsdl.org/Tutorials/TextInput for more details, but
start will show keyboard, stop will hide it, and rect lets SDL move the
window to keep the text input box in view. This can be quite janky it
seems, so use with consideration. Especially (like in the 0_sink
test..) near the edges where the keyboard would show.
Binaries; mac, android, iOS updated. windows/linux still pending