Closes #703
Closes #1358

This means

* Adding new configuration toggle `CATCH_CONFIG_DISABLE_EXCEPTIONS`
and a best-guess configuration auto-checking for it.
* Adding new set of internal macros, `CATCH_TRY`, `CATCH_CATCH_ALL`
and `CATCH_CATCH_ANON` that can be used in place of regular `try`,
`catch(...)` and `catch(T const&)` respectively, while disappearing
when `CATCH_CONFIG_DISABLE_EXCEPTIONS` is enabled.
* Replacing all uses of `throw` with calls to `Catch::throw_exception`
customization point.
* Providing a default implementation for the above customization point
when `CATCH_CONFIG_DISABLE_EXCEPTIONS` is set.
* Letting users override this implementation with their own.
* Some minor changes and ifdefs all around to support the above

This is a first step towards support a no-exceptions mode

This avoids instantiating the member-setting function template
and checking the invariants in cases where we know the invariant
already holds.

This avoids having to include <stdexcept> in the main include path
and speeds up the compilation if Approx is used with multiple
different types.

Fixes #1374

issue #1360

It is possible to have multple  given contexts in a single BDD scenario;
if you have to type 'and' in the GIVEN description; it's very likely you
need an AND.

A generic AND  is not possible, thus a AND_GIVEN  is added to complement
the AND_WHEN and AND_THEN.

Can be used without needing to increase indent:

	SCENARIO("...") {
		GIVEN("...")
		AND_GIVEN("...") {
			WHEN("...") {
				THEN("...") {
					// ...
				}
			}
		}
	}

would correctly output, when requested/needed:

    Given: ...
And given: ...
     When: ...
     Then: ...

The padding had to be increased by a character in the output message, to
continue to be uniform.