Make headers conform to package.el requirements
We'd like to add a scion package to MELPA, but the headers (and footer line) are not package.el-compliant, so an installable package cannot be built. This commit reformats the header slightly, and adds the required trailing "ends here" line.
Add an autoload cookie for scion-mode.
There's no need to require all of scion.el before a Haskell file is loaded.
Add compatibility for GHC 7.2.x and GHC 7.4.x
Add compatibility for GHC 7.2.x
No code changes were necessary to be able to compile it with GHC-7.4.0 as it already compiles with GHC-7.2.x thanks to Mitsutoshi Aoe's work on that.
This flag will be needed by upcoming atto-lisp.
Main change: files opened from the session view automatically set `scion-current-session' to the session they were opened from.