Before, such code `if (slices_equal() & status == 1)` was parsed
as `if( (slices_equal()&status) == 1 )`.
Note, that this change leads to hash changes of some verified contracts,
but a new priority is more expected from the user experience.
Note, that I have not added all builtin functions.
I filtered out strange and actually unused in practice,
like "int_at()" and similar, or "run_method0()" and similar.
(Probably, they should be dropped off even from builtins)
Also, I've modified some stdlib.fc legacy tests just to ensure
that a resulting hash doesn't change.
