Peter M. Groen / cxxopts

This closes issue #20.

Reorder the `parse_value` functions so that the vector-specific
function can see all of the other specific parsers.

Also use single character \n for end of line instead of string literal.

* Add cxxopts.hpp as a source file to executable
* Add msvc options for compiling
* Add CXXOPTS_BUILD_EXAMPLES option to CMake build
  * This is helpful when using CMake's ExternalProject_add()
  * It is ON by default, but configurable from the command-line.

Don't count default values

Remove log output

README.md: Fix compile errors in quick start example

Looked like it was left over from something? Saw it when testing "--some-int-val string"

Fix Clang -Wsign-conversion and -Wshorten-64-to-32 warnings.

cxxopts in biicode

Better support for spaces

This fixes support for options such as --file="folder with spaces/file".

Fix remaining character check