Cygwin note to Makefile

Cygwin 'make dist' now works, and 'make dist-src' works as long as
you have 'zip' and 'mkisofs' installed.
Merge branch 'makefile-cygwin-note'
Make DUK_CMDLINE_BAREBONES the default

This will make it more probable that the initial compilation works without
investigating a linker error.

Ideally the Makefile would detect readline availability, but that would
require `uname` or some other platform hackery, which is probably too
heavyweight for a simple example Makefile.
Guide fix for new DUK_CMDLINE_BAREBONES default
Merge branch 'barebone-cmdline-default'

Maked DUK_CMDLINE_BAREBONES the default to avoid awkward linker errors
when user first tries to compile the commandline tool on a non-Unix
platform.
Fix plain use of fpclassify() and FP_NORMAL

Broke Windows build.
Merge branch 'fix-plain-fpclassify'
Bump DUK_VERSION for 0.12.0 release
Release note: estimated v0.12.0 release
Release note date tweaks