(MESS) ti85: add basic support for the TI-84 Plus

Adds known dump of TI-84 Plus which has been sent to a mess dev and supports
enough asic functionality that it boots and runs.

Fixed up model enum to match style from the apple2 and used it to add support
for where the ti84p differs from the ti84pse.

Consolidated code for the 15Mhz calculators so there is less duplicated code
between the ti83pse, ti84pse and ti84 support code.
Support for the BEXT instruction

The BEXT instruction is needed for the Unisonic Champion driver which I'm building.
The Intellivision doesn't need it since its EBCA0, EBCA1,EBCA2 and EBCA3 pins are grounded.
The method used was a suggestion from RB
Support for the BEXT instruction (part2)

The BEXT instruction is needed for the Unisonic Champion driver which I'm building.
The Intellivision doesn't need it since its EBCA0, EBCA1,EBCA2 and EBCA3 pins are grounded.
The method used was a suggestion from RB
Merge branch 'ti85_changes_for_upstream' of https://github.com/Jonimoose/mame into Jonimoose-ti85_changes_for_upstream
Merge branch 'Jonimoose-ti85_changes_for_upstream'
Merge branch 'patch-2' of https://github.com/plgDavid/mame into plgDavid-patch-2
Merge branch 'plgDavid-patch-2'
Merge branch 'patch-3' of https://github.com/plgDavid/mame into plgDavid-patch-3
Merge branch 'plgDavid-patch-3'