GXemul Code2

Introduce a ToInteger(), in addition to ToString().

Better fix for not showing base-class-only components in help/documentation etc.

Do not list base-class components in the help, documentation etc, since they cannot be instanciated.

Unbreak build; the UNITTESTS(className) case is special (used in GXemul.cc).

Oops, MIPS PROM is of course at physical 0x1fc00000, not 0xffffffffbfc00000. :-)

Updating Doxygen class comment for MainbusComponent: child components should be MemoryMappedComponents.

Adding some TODOs about automated documentation generation.

Minor updates to the Doxygen class comment for MemoryMappedComponent, and to the Source code documentation Main Page.

Minor documentation fix.

Adding a MemoryMappedComponent base class, which all memory-
mapped components should inherit. (The canonical example is
the RAMComponent class.)

The MainBusComponent can now forward reads and writes to
memory-mapped child components.