Various cleanup and made a splash screen for startup.

Made setup macros to make things more clear during startup.
Added in constants for ram and rom segment.
Made macros into procedures for int21h to be consistent with other interrupts.
Fixed the scan->ascii table.

'A' and 'B' were switched, and also while shifting out the unused bit,
the register was not properly restored.
Started using ramSegment definition.
Cleanup of lcd code is in progress.

It currently works to initialize the keyboard, and you can print characters
one by one to the screen with proper text wrapping.
Need to figure out how to print to memory and then refresh the screen.