Exported variable string operand into the Sieve engine itself as 'catenated string' (for similar use in other extensions like the testsuite).

Previously the final value of internal variable was for every store action that didn't
specify a :flags argument explicitly. This results in out-of order assignment/removal
of flags, e.g. also the flags assigned keep actions that were executed before the
addflag/setflag command were modified.

Enforced limits on string length and handled the finite nature of integers for number parsing and the construction of the AST.

Working towards improving the handling of currupt binaries: defined multiple exit codes for execution functions and defined trace macro for reporting binary corruptions.

RECOVERED FROM INCONSISTENCY: developed testsuite and binary dumping and fixed various small issues.

Added support for reading an entire stringlist into memory. Also fixed various identical bugs in stringlist-related error handling.

Properly implemented the code dumper. Dumps are now printed in a stream. The individual opcode and operand implementations no longer use printf()s.

Exported sieve-code-dumper from sieve-interpreter containing all code dumping related implementation. Now to remove all printfs....

Fixed bug in handling optional operands to opcodes that have no mandatory operands (0 is no longer a valid opcode)

Grouped runtime parameters into a single runtime environment and started implementation of result composition/execution.