Move scheme-adapter.sh wrapper scripts into a subdirectory.

--HG--
rename : script/haney.sh => script/wrapper/haney.sh
rename : script/huski.sh => script/wrapper/huski.sh
rename : script/mignon.sh => script/wrapper/mignon.sh
rename : script/miniscm.sh => script/wrapper/miniscm.sh
rename : script/plt-r5rs.sh => script/wrapper/plt-r5rs.sh
rename : script/tinyscheme.sh => script/wrapper/tinyscheme.sh
Tweaks to docs.
Pixley 2.0 removed `cadr` and `null?`, so remove them from mignon.
Possible doc tweak.