starting v3 by removing functors (a lot of other parts are temporarily disabled).
add mathfuns.jl
add mathfuns.jl
remove old codegen
add / and \ as binary sewise operations
add extree.jl for construction of expression trees
remove isewise function
implemented extree & tested up to range expressions
extree on reference expressions tested
add tests over is_scalar_expr
ewise map tested
rename EMapCall --> EMap, EReducCall --> EReduc
extree on reduction call tested
add show methods for extree components
Corrected way to process scalar expressions
reinstate functors.jl
Merge branch 'functor-rename' into v0.3-wip

Conflicts:
	src/NumericExtensions.jl
	test/test_functors.jl
add new test cases for extree on composite of reduction and map
Merge branch 'master' into v0.3-wip

Conflicts:
	src/NumericExtensions.jl
remove max/min from the list of unary reduction functions