CPCEC, ZXSEC and CSFEC

What's New:

-- minor patch adding RUNEC, a file helper that takes a file as a parameter and launches the emulator that can read it, and fixing many warnings caused by questionable programming styles. The SDL2 version fixes double keypresses when redefining the joystick keys while debugging, as well as a crash when compiling the emulators with small window sizes. The common CDT/TZX/PZX player performs sanity checks on blocks $19 and $2B. The Z80 module relies on a new macro, Z80_DUMB to perform dummy reads. CPU clock options are no longer based on 1x, 2x, 3x and 4x, but on 1x, 2x, 4x and 8x. Autorunning a tape disables disc drives only when rebooting the system, instead of disabling the drives until a reset. CSFEC fixes two bugs in the VIC-II (reading register 26 must always set the top four bits: "HVSC 20 Years"; writing register 17 with the same old value must not remove the border: "Paradroid") and another one in the snapshot loader (pending CIA2 events were sent to CIA1) when loading snapshots. MSXEC now reads the file MSXEC.SHA as text instead of binary (reported by CPCbegin). ZXSEC can save Z80 snapshots (version 3), compression is optional. The package includes two new files, CSFEC-3B.VPL for CSFEC and MSXEC-3B.VPL for MSXEC; users can edit them to implement new colour palettes.