tex-mf2pt1{,-doc}: update to 2.7

Version 2.7 of mf2pt1 supports new --output-dir and --save-temps options
for controlling where intermediate and output files are written and if
intermediate files should be retained after execution completes.  It also
allows helper programs (mpost, t1asm, and fontforge) to be overridden,
including with arguments, via environment variables.

(markd)