Added InchCoordProxyTests#testProxyValidityFlagPersistence

• New `testProxyValidityFlagPersistence` test that starts similarly to `testInstanceAndProxyValidityFlags` but instead of setting a value (and thus validating the inchCoord/Proxy) it immediately releases the `inchCoord` and test that the `inchCoordProxy` has the correct flags.
	» This test is essentially an alternate version of `testInstanceAndProxyValidityFlags` where `inchCoord.doubleValue` never gets set.
• Added step to `testInstanceAndProxyValidityFlags` that test `inchCoordProxy`'s flags after `inchCoord` has been released (to match `testProxyValidityFlagPersistence`).

Minor:
• Updated function comment for `testInstanceAndProxyValidityFlags` and added a similar one to `testProxyValidityFlagPersistence`.