Significant change to Stepper motor device behaviour, using devcb2 interfaces.

New functions added:

 MCFG_STEPPER_ADD(tag) - add a stepper device
 MCFG_STEPPER_REEL_TYPE(type) - the equivalent of the first line in the old interface, now also takes NOT_A_REEL for printer and similar applications
 MCFG_STEPPER_START_INDEX(int index) - the old second line of the interface, the position (in half steps) where the optic tab first triggers.
 MCFG_STEPPER_END_INDEX(int index)  - the old third line of the interface, the last position (in half steps) where the optic tab triggers.
 MCFG_STEPPER_INDEX_PATTERN(int pattern) - a coil pattern in hexadecimal that has to be on the motor for the index to trigger (0 if no specific pattern is needed)
 MCFG_STEPPER_INIT_PHASE(int phase) - starting phase of the motor

All drivers have been updated, testing done to all specific drivers - Scorpion 4 was particularly complex. [James Wallace]
(nw)
fixed Visual Studio compilation and compilation in general / small r10788_device initialization cleanup (nw)
MZ-2500: Fixed floppy drive reverse behaviour, allows Laydock to get farther [Takeda Toshiya, Angelo Salese]
machine.c: the majority has spoken (nw)
init order issue (nw)
qt/debug: Device tree view.  Looks cool with mu100 or lindbios [O. Galibert]
Fixed racingb save state problem (nw)
Quick testing didn't show any problems with other games using the chip, but we'll see on the next save state regression test..
Added missing save state support to segaic16_video_device. Fixes quartet2 save state problem (nw)
Some almost exclusively cosmetic changes to the device, while at it (nw)
Fix yamyam and clones regression from clock change. (nw)
windows too (nw)
tms5110.c: implement output and read bit commands. [Lord Nightmare]
Merge branch 'master' of https://github.com/mamedev/mame
tc0480scp.c: revert postload change for now, needs more investigation (nw)
Various, mainly Taito drivers: clean up banking, remove unneeded postload callbacks (nw)
(MESS) Fix VSM rom read through the tms51xx, and add tms6100 hookup to tispeak.c, fixing speech in speak and spell and speak and math. The drivers are usable but no display yet. Fixed speak and spell clock speed (it is 1/2 the clock input of the tms51xx chip) [Lord Nightmare]

Non-Whatsnew Note: this commit breaks the speech in radar scope trs02 set (because the rom it has has the bits in the backwards order). I will fix this later.
fixed status being reset too early
Using IRQ_CALLBACK_MEMBER for irqs in MZ-2500, nw.
tc0480scp.c: save state fix (nw)
(MESS) excalibur : starting to add floppy support (nw)
(note: using old wd17xx because new wd crashes when the disk is loaded up)