Implement Cross-Compilation on the SDK

[ErikMcClure]

Once we add ARM (#16) and PowerPC64 (#7) architecture support, cross-compilation support should be added to the SDK. The SDK needs to separate the fully featured runtime from an embeddable runtime that has only a single architecture and minimal features. This could potentially be accomplished either by statically compiling the cross-compiling runtime into innative-cmd, but this limits how people might utilize the library.

What will likely happen is that a third "Release Embed" option will be added with a -e extension, so a minimal innative-e.dll will be available for embedding into programs, versus the more heavy duty cross-compilation runtime.

Cross-compilation should add ENV_STATIC_LIBRARY to compile static library files, since it will now be possible to compile to arbitrary CPUs.