guile: use install_symlink
ksh: use install_symlink

As a bonus, fix the broken ksh.1 symlink.
Don't load the full debugger when readline is the formula being installed

Fixes #27842.
lesstif: use Homebrew's freetype
grace: lower optimization to fix miscompile with clang 3.4

cf. #27840.
Scala 2.11.0-RC3
scala: add 2.10.3 bottle.