Optimize manifest.add
Testing shows that manifest.add is spending a significant percentage of
its time running calcoffsets and doing text = "".join(addlist). This
patch removes the need for both of these by storying the manifest in a
character array, and using a modified bisect search to find lines without
the help of a separate index of line offsets.
manifest.add was also reworked to push delta construction/combination into the
main loop.
Time to apply 2751 patches (without psyco, ext3 noatime,data=writeback):
Stock hg: 4m45s real 3m32s user 55s sys
patched: 2m48s real 1m53s user 43s sys
quilt: 2m30s real 45s user 50s sys
(quilt does much more io...)
