ETHER: Fix to allow proper building and operation when networking support is undesired or unavailable. #143
sigma: Fix shutdown/detach issue with tape devices.

Also add makefile and Visual Studio Project definitions to build the incomplete/unsupported sigma and alpha simulators.
VAX: Allow potentially pending console output to be delivered prior to halting back to the sim> prompt
VAX: Added support for the DEQNA device on Ultrix 1.x. Henry Bent observed that the deqna driver in this OS counted on older DEQNA firmware which automatically enabled interrupts after a software reset.

CPU Idle detection for this OS is now supported and the combination of SET CPU IDLE=ULTRIX-1.X and explicitly using a DEQNA device (SET XQ TYPE=DEQNA) will enable the automatic enabling of device interrupt generation.
ETHER: Fix asynch reader thread rundown in error recovery path.
MicroVAX I: Fix to allow reboot when the initial boot didn't specify a boot device (i.e. a sniff boot)
VAX: Make sure that Ultrix 1.X specific behaviors are only in effect with that OS
Compiler suggested cleanups - Johnny Billquist
VAX8600: Fix for console I/O from Johnny Billquist

Writing to the TXCS register always updated the transmit enable mask, even when the "Write Mask Now" bit was not set. That bit needs to be set for the write to the register to actually update the transmit enable mask.
Compiler suggested cleanup
Fix to avoid excessive compiler optimization of MicroVAX II ROM access spinwait.  Found by Cory Smelosky and Jordi Guillaumes Pons.

Used same solution as the MicroVAX 3900 ROM access logic suggested by Sergy Oboguev in April 2012.
MAKEFILE: Added support to attempt to use the OS provided cc if gcc isn't available or otherwise specified by GCC= on the make command line.
MAKEFILE: Fix gcc availability test for more/most platforms
WINDOWS-BUILD: Fix buildall to work on platforms which have multiple versions of Visual Studio installed

- Added checks for dependencies before execution
- Added setup and update support for local Win32-Development-Binaries repo init
- Added support for operation under both a CMD.EXE invoked from either a git bash process or a natural windows CMD.EXE
- Fixed proper operation for first build operation after the local build repo has been cloned
- Make sure the build is of the latest code in the master branch from the origin repository
VMSBUILD: Fix minor issue building the ssem simulator on VMS host platforms
MAKEFILE: Add support for building under Haiku

Find the header and library paths with findpaths.

We need -lnetwork for sockets.

We do support pthread, it's in libroot.

We do support dlopen, it's in libroot.
Work around missing nice() on Haiku
Haiku has socklen_t
VAX, PDP11: Fix VHD support to save the correct updated part of the Block Allocation Table (BAT) when new blocks are added to a VHD.
VAX780: Added idle support for SysVR2

A new idle mode (SYSV) is now available:

    sim> SET CPU IDLE=SYSV