Changes

180728
	- run.c: fixed MOVE
180727
        - io.c: fixed MIX binary I/O, file access modes

180726
        - main.c: set object deck title
        - run.c: reset PC only when GO button is pressed
        - main.c, io.c, run.c: fixed GO button, text encoding on Windows, MOVE instruction
        - opcodes: added floating point opcodes, different encoding for AND, OR, XOR, INT
        - cell.c: floating point operation stubs
        - asm.c: punch_object searches for not empty cells
        - run.c: silence GCC warnings
        - io.c: fixed io_pending_interrupt()

180725
        - asm.c, main.c: punch object deck
        - run.c: count XEQuted instruction time
        - run.c, io.c: added wait state, interrupts are serviced by priority
        - mix.h: device types are reordered by priority
        - main.c: added '-e' flag to set entry point, '-c' for core memory
        - mixref.pdf: CP-M, XEQ instruction added
        - run.c: added CP-M, XEQ, check configuration flags
        - io.c: interrupt facility flag removed
        - main.c: usage, mix_config flags

180718
        - run.c: CPU trace, status display fixed, indirect addressing
        - mixref.pdf: JrE, JrO, NEG, XCH, SLB, SRB, OR, XOR, AND added
        - opcodes, cell.c, run.c: several UT-MIX extensions added

180717
        - mixref.pdf: INT instruction added
        - io.c, main.c, opcodes, run.c: interrupt facility added
        - io.c: bad busy time condition fixed

180124AP
        - io.c: tape IOC time calculation

180123AP
        - mixref.pdf: octal codes
        - io.c: low end Burroughs B5500 peripheral timing
                tyme is 2us access time for B461 memory module
                drum restricted to   64 blocks (6,400W)
                tape restricted to 7680 blocks (7,680,000W)

180118AP
        - io.c, run.c: track idle time waiting for I/O to complete
        - run.c: instruction execution trace, memory dump

180118AP
        - run.c: memory_fetch/store, safe_fetch/store checks incomplete I/O
                 MOV changes elapsed_time, do_scheduled_io() takes into account
        - symbol.c: MinGW has stricmp()
        - io.c: buffers are protected for write/read access
                output operation locks buffer for READ
                input operation locks buffer for WRITE
                buffers cannot overlap, except for output operations
                safe_fetch/store enforces this access for the MIX CP as well

180117AP
        - io.c: go device, reader/punch/printer could redirected to files
                only tape/disk/drum device files contains device numbers
        - run.c: go device support, execute IN 0(U), start from 0
        - main.c: switches
                -g device       set GO device
                -h              help
                -r              redirect reader/punch/printer to files
        - run.c,io.c: busy I/O devices, simulated I/O time
        - run.c: flush outstanding I/O at HLT
        - added mixref.pdf

180116AP
        - changed delta, sigma, gamma to ~, [, #
        - charset.c: card cannot read/punch: sigma, gamma, $, <, ...
                     (20, 21, 49, 50, ...)
        - io.c: overpunch (11-punch) in card reader
        - driver.c: ALF is a synonym to CON
        - parse.c: parse_expr() do not clobber overflow