trying to build with 2.10-M5

stuck on SI-6100. gadt pattern matching becoming a nuisance.
M7 builds and tests
Merge branch 'delite-develop' into delite-develop-M7
use scalatest M7
more work on stencils

first example working: reuse values computed in one loop iteration
in the next by storing it in variables.
fix static data in nested scopes
emitFileHeader for imports and the like
add a flag to ScalaCompile to dump generated code to stdout
sliding window stencil working, with expected output and bytes/flop ratio for shonan challenge problem
now using for comprehensions and side-effecing writes
add non-sliding version for comparison
minor cleanup
expose staticData interface
minor cleanup
add `unchecked` to emit arbitrary, unchecked Scala code
experiments with dynamic recompilation

Introduce `stable` vars. Programs are compiled assuming that stable
vars are mostly constant. Programs are specialized to the current
values but every read is replaced by a guard that will trigger
recompilation of the program if the var has changed.

The tricky part is recompiling the program on the fly, because
when we detect a var change, we are already in the middle of
executing compiled code. This is solved by storing the uncompiled
continuation as static constant. Additional care must be taken to
deal with the free vars of the continuation, which may point
to local vars of the running compiled code. We thus generate
instructions in the original code to pass these vars to
the dynamic compile call.

There are considerable degrees of freedom regarding when to
compile, what compiled code to store/throw away etc. The test
cases explore just one design.
test case for Delite code motion issue
enabling codemotion changes. tests pass.
Merge remote-tracking branch 'origin/delite-develop-m7' into delite-develop2
fixed OrderingOps mirror for M7