Allow the user to execute commands at the beginning of the X session.

The difference between xsession and xprofile is that xsession is exec'd and xprofile is sourced.
So with xprofile all commands after sourcing will still be exectued. This allows for instance
autostarting of applications while configuring the start of a window manager via configuration.nix.
openjdk: Build only once

Since javac doesn't do much optimisation, bootstrapping twice is
unlikely to produce a faster compiler.
openjdk: Remove obsolete header file hack
openjdk: Fix manpage cleanup
openjdk: Skip configurePhase

The build phase also runs "make sanity", so there is no need to do it
twice.
openjdk: Use multiple outputs

This unifies the "openjdk" and "openjre" packages.  The JDK is placed
in the "out" output, the JRE in "jre".

Also, everything is now stored in $prefix/lib/openjdk, so the JDK/JRE
no longer pollute user environments with files like
"ASSEMBLY_EXCEPTION" at top-level.
jikespg: Cleanup
hydra-ant-logger: Fix the build
postgresql-jdbc: Update to 9.3-1100
ant: Update to 1.9.3

Also, Ant no longer has a build-time dependency on a particular JDK.
It finds the JDK via $JAVA_HOME or $PATH (by looking up javac).  This
way, we don't need to have separate packages like apacheAntOpenJDK and
apacheAntOracleJDK.  It also seems reasonable: after all, installing
GNU Make doesn't give you a C compiler either.  It does mean that
instead of

  buildInputs = [ ant ];

you now need to write something like

  buildInputs = [ ant jdk ];
kaffe: Remove

It no longer builds and doesn't seem very maintained.
jedit: Fix build
freenet: Fix build

Also change the name attribute from "freenet-official" to "freenet".
postgresql-jdbc: Fix build
hydra-ant-logger: Fix build
clojure: Update to 1.5.1

Also, merge the wrapper into the main package, and get rid of the
binary variant.
clooj: Update to 0.4.4

Also, merge the wrapper into the main package.
icedtea: Remove

It has apparently never worked.  Also drop xerces and xalan, which
were only used by icedtea.
Fix some references to apacheAntOpenJDK
fop: Drop runtime dependency on the JDK