[jam] Set ARCH defs like we do for the runtime.
Adding a function stream-console?
Merge pull request #506 from iglennrogers/isatty

Adding a function stream-console?
[docs] Replace ``<foo>`` with :drm:`<foo>` for all DRM classes.
[io] Fix bug in accessor-console? on win32.
Merge pull request #507 from cgay/docs

[docs] Replace ``<foo>`` with :drm:`<foo>` for all DRM classes.
Use OPEN_DYLAN_PLATFORM_NAME to set LIB dirs.

OPEN_DYLAN_PLATFORM_NAME is available to JAM as TARGET_PLATFORM.

We were using OS and OSPLAT, but using OPEN_DYLAN_PLATFORM_NAME
will make things more consistent and work with things like
emscripten and the Java backend. It also makes cross-compilation
work again by just setting OPEN_DYLAN_PLATFORM_NAME and everything
else working from that.
Export target-platform-name, re-use it.
Rename OPEN_DYLAN_PLATFORM_NAME to OPEN_DYLAN_TARGET_PLATFORM.
Release notes for OPEN_DYLAN_TARGET_PLATFORM.