FFT for ARMv6

This library is being created as I have a need to do very fast FFTs on low end devices not supporting the NEON instruction set.

The Raspberry Pi is an ideal candidate for developing in gcc before porting to JNI for low spec Android devices, hence it's inclusion.

Fixed point 16/32 integer FFT library suitable for the Raspberry Pi and Android devices.

Includes test stubs for gcc on the Raspberry Pi and a Basic4Android wrapper from JNI.

It includes hand optimised ARMv6 assembler, demonstrating techniques such as pipeline stuffing to achieve maximum performance.

It also demonstrates how to include large chunks of assembler inline with C/C++ thus avoiding ABI issues between platforms.