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.

Made lda plugin properly refer to the main script as 'main script' and not the basename of the sieve file (which is of no interest to the user for the main script).

Fixed TODO: made sure main scope used in variables dumping is unreferenced when code dumper is freed.

Fixed amd64 logging segfault; turns out using same va_args in multiple vprintf calls is not possible.