GXemul Code2

More TODO updates.

increase_refcount, decrease_refcount, and release() should be non-public.

Updating TODO about instabilities in the cycle scheduling mechanism.

Adding flush() calls to stderr and stdout, in an attempt to improve clarity in test output during failures.

Scrapping the "plugin" concept; the already existing component framework should hopefully be enough as it is.

Adding a test to PluginDescriptor to make sure that reasonable/planned descriptors work as expected.

Adding a PluginDescriptor class, for parsing plugin descriptor strings (component:plugin(args):filename etc).

Moving the multiple identical instances of SplitStringIntoVector to the StringHelper class, and adding some unit tests.

Moving the multiple identical instances of parse_number to a new StringHelper class, and adding some unit tests.

Updating the NetBSD/dreamcast version from 4.0 to 5.0.2.