Merge pull request #492 from cgay/regex-docs

Regex docs
[rt] Merge the run-time directories.

This doesn't merge actual functionality yet, that'll be in follow-up
commits.
Merge pull request #494 from waywardmonkeys/combine-runtimes

[rt] Merge the run-time directories.
[rt] Add OPEN_DYLAN_ARCH_* flags.
[rt] Add back definition for arm-linux.
[rt] Use OPEN_DYLAN_ARCH_X86.

This limits code to the correct platform.
Fix HARP runtime builds.
Merge pull request #495 from waywardmonkeys/combine-runtimes

Combine runtimes - Further fixes
[rt] Don't require C99.
Initial pass at a <trie> collection class.
trie, work in progress.  moving to Windows to debug.