Change range's 'by' functions for param strides

We have versions of 'by' that take the stride as a param in order to check at
compile time if the stride was 0 rather than waiting until runtime. However
this means that for all non-zero param strides a new function is stamped out
which adds bloat to the generated code. This just adds a "where step == 0"
clause to the functions so that we still get the compiler time warning without
stamping out a function for valid param steps.
Merge pull request #1027 from ronawho/change-range-param-by-funcs

Change range's 'by' functions for param strides

[ok'd /suggested by @bradcray in pr: 1021]

We have versions of 'by' that take the stride as a param in order to check at
compile time if the stride was 0 rather than waiting until runtime. However
this means that for all non-zero param strides a new function is stamped out
which adds bloat to the generated code. This just adds a "where step == 0"
clause to the functions so that we still get the compiler time warning without
stamping out a function for valid param steps.