layer conversions.

definitions until cmake was run twice.  This was causing some projects to not
build properly.

easily used in multiple cmake files.

Adding an install target to dlib's CMakeLists

appears as a huge and obvious orange button.

'Hide' dlibConfig.cmake to prevent Windows' CMake to wrongly consider the build directory as dlib install prefix

On Windows, though, only install the static library as dlib does not
generate any useful shared library on Windows.

This allows external project to include dlib by simply using
find_package(dlib REQUIRED)
and:
include_directories() / target_link_libraries(your_target )

Install the static library along the shared one.

The name of some CMake variables has been changed to
follow the naming in config.h (and thus get the special #cmakedefine
directives to work as expected in config.h.in)

Implementing the design discussed in issue #34 (ie, installation only
in Release mode, for unix platforms).

set_ptrm().

allow assignment statements with mixed dlib::matrix and mat(T*) expressions
that might alias each other.  Also updated BLAS bindings to bind to set_ptrm()
assignments.