maybe nitpicky, but I think it's more correct. changed 'and' to 'or'.
added commas, and made some minor wording changes.
edited sentences (and a paragraph break) for clarity.

Some parts in here, I had to reread the text a couple times to make
sure I understood. I think it is clearer the way I've changed it.
Prevent crash on startup. Preliminary fix! I still need to actually reproduce original crash!
https://github.com/darktable-org/darktable/pull/548#issuecomment-42763922
Merge pull request #557 from Terrycloth/clarifying-text-in-user-manual

my first few edits to the user manual.
usermanual: more on tagging (thanks to Christian Kanzian)
Revert "Prevent crash on startup. Preliminary fix! I still need to actually reproduce original crash!"

This reverts commit f6129f8a352dd99037d98d5f8c51680ffb889ada.
Preset update infrastructure: some modules(e.g. lens iop) depend on global data in reload_defaults()

module->init(module); is already called by dt_iop_load_module_by_so()
Lens IOP: prevent crashes in legacy presets update infrastructure
Levels IOP: add automatic mode

Now you can set black/gray/white percentiles, and store as a preset -
will work as expected.
Fix issues with zooming :)
wip