extending TExpr
testing texpr
texpr tested
test_tmode passed
generalizing reference expressions
added ju_expr
modified meta_tools
1D, column, and row references tested
2D ref tested
tests on ref-expressions all passed
ewise expressions passed
op-assignment tested
special handling of scalars tested
full reduction tested
reduction, block, and hybrid expressions tested
Merge pull request #17 from tshort/master

Add @devec_transform for devectorizing operations with associative types
extensions incorporated (conflicts resolved)
Rename DeExpr ==> Devectorize everywhere (all tests passed again)
Bug fix for @devec_transform (it didn't work except for variables
named d!).