[ sharing ] documented call-by-need evaluation in release notes
[ new ] Additional arguments to `tactic' are now inserted after the context and goal type.
Add make targets for HPC.
Un-relativize undefined.h in good ol maint too.
[ docs ] Emacs mode hacking goodness
[ docs ] Reference HACKING in README.md
Fix whitespace.
[ refactor ] represent meta instantiations without the lambdas

This lets us perform instantiation using parallel substitution rather
than iterated beta reductions.
Merge remote-tracking branch 'origin/maint-2.4.2'
[ issue1323 ] fixed: added missing ignoreSharing
[ sharing ] reduce number of indirections when updating pointers
[ issue1324 ] fixed: speculative inversion didn't reset the state properly
Merge remote-tracking branch 'maint-2.4.2'
Merge remote-tracking branch 'origin/maint-2.4.2'
[ fix ] bad merge