obsolete: use parsers.fm1readmarker if it exists for a ~38% perf win This moves perfloadmarkers on my linux workstation (63494 markers from mpm, crew, and myself) performance from ! wall 0.357657 comb 0.360000 user 0.350000 sys 0.010000 (best of 28) to ! wall 0.222345 comb 0.220000 user 0.210000 sys 0.010000 (best of 41) which is a pretty good improvement. On my BSD machine, which is ancient and slow, before: ! wall 3.584964 comb 3.578125 user 3.539062 sys 0.039062 (best of 3) after: ! wall 2.267974 comb 2.265625 user 2.195312 sys 0.070312 (best of 5) I feel like we could do better by moving the whole generator function into C, but I didn't want to tackle that right away.

parsers: add fm1readmarker This lets us do most of the interesting work of parsing obsolete markers in C, which should provide significant time savings. Thanks to Martin von Zweigbergk for some cleanups on this code.