Deleted binding target's copy ctor and assignment operator.
Changed ci_signal_e to cie_signal.
Added nscast, abbrev legend to casts.
vec's conversion ctor now uses ncast.
Fixed compile bug in nscast, no longer constexpr.
Conditionally added c++14 versions of equal for earlier versions.
Added forwards to meta-lib.
Range updates.

- The ctor taking t_range_t const& does not necessarily come from a range_c.
It is now treated as an unparameterized container.
- Added proper conversion ctor from ranges of other iterator types.
- Fixed conversion warning in size().
- Added asserts to make sure mp_begin is always <= mp_end in all places where
data comes in from external sources.
string_ref_c updates.

- Added const accessor for getting the range directly. This is comparable to
getting begin/end pairs.
- Fixed conversoin ctor fom string.
- Bashed reverse. It doesn't work as expected.
- Added ostream inserter.
range_c updates.

- Fixed typo in conversion ctor.
- Added flag range() functions ala flat begin()/end() functions to get
the range from a container.
Added string-ref.cpp to meta.mk.
Fleshed out most of view_c base.