[util][math] add sqrt function in bg::math namespace; this function
calls std::sqrt for fundamental number types and ::sqrt for everything
else; it helps avoiding implicit conversions for fundamental number
types when ::sqrt is called (in particular, we avoid the conversion
from long double to double when ::sqrt is called);
[util][math] update copyright header
[strategies] replace calls to ::sqrt by calls to bg::math::sqrt
[strategies] fix unused typedef warningy
[algorithms][equals] fix copyright years; replace call to ::sqrt
by call to bg::math::sqrt
[extensions] replace calls to ::sqrt by calls to bg::math::sqrt;
change has not been applied to projections and ttmath;
[extensions][algorithms][offset] remove obsolete include (file no
longer exists)
[util][math] fix return type of sqrt for fundamental number types
Merge branch 'develop' of https://github.com/boostorg/geometry into feature/math-sqrt
Merge branch 'feature/math-sqrt' of github.com:mkaravel/geometry into feature/math-sqrt
[util][math] fix return type for math::sqrt; fix implementation
for sqrt for non-fundamental types (use the using mechanism);
[test][util] add unit test for math::sqrt
Merge branch 'develop' of https://github.com/boostorg/geometry into feature/math-sqrt

Conflicts:
	include/boost/geometry/algorithms/detail/buffer/buffer_inserter.hpp
Merge pull request #56 from mkaravel/feature/math-sqrt

Feature/math sqrt
[buffer] Remove buffer_piece_collection_with_mapper
this was a debugging tool. It is now replaced by a visiting policy (like
in partition), and implemented in the unit test itself
[buffer] remove unused functionality
[buffer] remove debug functionality
The lines which are warnings are now protected by BOOST_GEOMETRY_DEBUG_BUFFER_WARN
Merge branch 'develop' of github.com:boostorg/geometry into develop
[buffer] move (dispatch) code for multi to buffer_inserter itself
This also tags the cast to multi_tag
[buffer] rename check_original to turn_in_input
comparable to point_in_geometry.
This removes multi_buffer_inserter