Add testLit168 for issue #168. Requires investigation.
Add explicit test for LitAsPort168.
Merge branch 'lit168' into litport168

Conflicts:
	src/test/scala/StdlibTest.scala
Fix for Issue #168 - lit as port breaks chisel.

Specifically allow UInt Literal TypeNodes.
This could possibly be restricted to top level nodes.
Fix issue #168 - lit as port breaks chisel - flag it as a ChiselError.
Wrap LitAsPort in try/catch since we now expect it to fail and require ChiselErrors be non-empty to pass.
fix a problem of poking negative numbers
Merge pull request #317 from ucb-bar/partition315

Two fixes for issue #315 --allocateOnlyNeededShadowRegisters breaks code, eats a register
Merge branch 'master' into litport168
Merge pull request #318 from dadeba/fixpokenegative

fix a problem of poking negative numbers
Pass "-C <targetDir>" to make - issue #319.
Merge pull request #320 from ucb-bar/makedir319

Pass "-C <targetDir>" to make - issue #319.
Revert "fix a problem of poking negative numbers"
Revert pr #318 - fix a problem of poking negative numbers.

This assumes it is more desirable to be able to poke large unsigned
numbers, than poke 32-bit signed numbers in hex format.
Merge pull request #323 from ucb-bar/pr/322

Revert "fix a problem of poking negative numbers" - #318
Merge branch 'master' into litport168
fix bfs & dfs
Add support for a constant pool.

Define literals as "static const" in the object and maintain a literal
pool.
Only output referenced nodes.

Rename internal flags.
Keep a set of reference nodes.
Add ability to enable --partitionIslands to test.