Merge the r986453 group from the performance branch.
See the branch for original log messages.
The STATUS entry for this group was: * r986453, r1029092, r1029335, r1030763 An even larger change: Speed up file translation by further optimizing the search for "interesting chars" and replacing EOLs only if they have actually changed (allowing for larger chunks of data per write output operation). The third patch fixes a svn_tristate_t comparison issue. Note: r1029092 and r1030763 are docstring changes. Justification: Apart from the physical I/O and the MD5 translation, this is the most CPU-demanding part of an svn export. This patch more than doubles its performance. It should also speed up svn checkout by the same amount (not factor) of time.