templater: create string unescape helper (
issue4798)
This gives us a unified place to do error-handling of string-escaping
syntax errors
parsers: use PyTuple_New and SET_ITEM to construct metadata pair of markers
With these 2 patches, fm1readmarkers() gets slightly faster:
obsolete._fm1readmarkers() for 78644 entries
58.0 -> 56.2msec
parsers: use PyTuple_SET_ITEM() to fill new marker tuples
Because we know these tuples have no member yet, PyTuple_SetItem() isn't
necessary.