reduce copies in LetCont.plug_reduce
just cache the stored value on the ModuleVar

no need to constantly do a full lookup during interpretation, it can't
change anyway
shortcut for making Values of size 1 (the common case)

somewhat hacky implementation
just pre-allocate the list instead of appending
shortcut the expensive use of label in this very common case
somewhat messily remove one level of indirection in label
simple primitives don't need a label to return their value

their is no potential for recursion
don't use slicing
correct ANF

implementation is quatratic in the depth of expressions for now
Remove duplicate W_OutputPort definition
Merge branch 'master' into loop-detection
Merge branch 'loop-detection' into loop-and-callgraph
Merge branch 'master' of github.com:samth/pycket
Merge branch 'master' into loop-detection
Merge branch 'loop-detection' into loop-and-callgraph