fixed emulation bugs in arithmetic instructions and made emulator treat HCF as an unknown opcode

Emulation of the following instructions was broken:

ASR - EX register calculation did not used signed value
MLI - did not set EX register at all
MUL - did not set EX register at all
added junit tests for all basic instructions (though not every addressing mode is tested with every instruction...)
fixed deadlocks on concurrent stopSimulation() / startSimulation() calls ... still not 100% safe though :/
Added more unit tests
support signed values in .dat
added license info
emulator now supports ignoring access to unused hardware device slots
configured license-plugin to ignore .dcpu16 / .dasm16 files
moved EmulationErrorExceptions from Emulator into separate package ; fixed emulator bug (STI did not wrap the registers after incrementing)
max. IRQ queue size is now honored , emulation of IAQ mixed up the meaning of the operand value,
disassembly view now supports scrolling using cursor-up/-down