remove const from encoding tables so we can change them at runtime
add --encoding-compatibility mode to prevent exceptions on operations between utf-8 and ascii-8bit strings

Conflicts:
	include/ruby/encoding.h
	string.c
import cibuild
st: pool allocation

Conflicts:
	common.mk
	gc.c
	st.c
add -github to version string
catch ipv6 multicast failures
skip crazy spawn tests
reduce parallel workers
put (development) in RUBY_DESCRIPTION instead of date/revision
use the FL_USER18 bit for RSTRING_HTML_SAFE
add per-class method cache