Memory optimisation

Pr. Piumarta various fixes

Add slice '[n:m]' for strings and array-like maps

an expression, add for in structure, refactor apply (merge with invoke),
transform millis to microseconds, mix boxed/unboxed integers

* Add try, catch, finally in the syntax

* Add throw, try, catch, finally mechanism in the interpreter

* Enhance runtime errors with file and line

* update test files

* Implement a FIFO for inputs

* Add working input stack with import statement

Various fixes