Added slurp_utf8($filename) which reads an entire file and returns its contents decoded from UTF-8 as a character string.
Added support for older MSVC C compilers by using __inline in place of the C99 inline keyword on pre-Visual Studio 2015 builds.
Fixed SSE2 detection to only enable the SIMD implementation on 64-bit x86 targets. This prevents unsupported SSE2 code from being selected on 32-bit x86 builds. Reported by Paul Howarth (@pghmcfc) issue #14.