* new mapping for interop api
* Fixed interop API mapping + added missing apis
* added engine apis
Imported from CityOfZion/neo-storm (ec5e6c8e2b587704a1e071e83b633d2d3a235300).
* support VM to pass method and arguments to a script.
* added support for type assertions in smartcontracts.
* added native vm support for print.
* moved VM API packages to vm -> API
* reverted the native Print opcode in favor of runtime.Log
* added support for registering custom interop hooks in the VM.
* Updated README
* Updated compiler with @OPTIMIZE tags
* Moved more tests to VM package.
* optimized and refactored compiler and vm API
* updated README with new smartcontract apis
* bumped version
* renamed test folders and fixed bug where wrong jump labels would be exectuted for rewrite.
* Added support for Osize (len(string)) and factored out the array tests
* Added current instruction number to VM prompt if program is loaded.
* added support for unary expressions.
* updated README of and sorted the help commands
* updated readme of the compiler
* bumped version -> 0.39.0
* implemented operation and param flags in the cli invoke cmd.
* reverted prev changes and added debug flag for compiling.
* change transactionType variable to Type, for package convention
* index support for arrays.
* implemented builtin (len) for the compiler.
* bumped version -> 0.35.0
* updated compiler README and changed invoke to testinvoke.
* implemented global variables.
* refactored imports + lots and lots of other sweet stuff + fix#28.
* Implemented the VM interop runtime API (GetTrigger, CheckWitness, ...)
