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Do something with this, better error checking?

- Parse arguments
- Look at args, cases:
   - --help
   - no files
   - no parent path
   - normal processing (ReaderT)

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- To change the app version:
   - Edit photoname.cabal:  version: xx.yy
   - Edit src/Photoname/Opts.hs, usageText near the bottom of footer
   - darcs rec these changes as "Changed version to xx.yy"
   - darcs tag "xx.yya"
     Use a, b, c as attempts for version xx.yy

   I'd like to make a script in util/ to automate this.
   After such a script has been made, may want to put developer notes on using it in doc/dev/<somefile>

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File serial number formats:

Panasonic:  P###0###.jpg
   First part is dir, second is serial. We can use the second part.
Canon:      img_####.jpg
   Can use the last 3 digits of this
Olympus:


Photo naming scheme (this info needs to go into usage help at some point)

yyyymmdd_[oth_]nnn[-e[n]].jpg

date: year month day
other author: 2 or 3 character initials
photo serial: last 3 digits of camera-supplied number, if possible
e or s: edited or sized, optional number for more than one
   -sp -ep : sized/edited for printing
   -sd -ed : sized/edited for desktop
   -sw -ew : sized/edited for web

Photo serial: Note that 3-digits is standard for Panasonic cameras. 4 digits is standard for Canon cameras. But we'll use 3 digits for Canon too, seems like unique within each day.


These files are arranged into a dir structure

top-level/
   0000/
      0000-00-00/
         00000000_001.jpg   -- Unknown pictures
         00000000_002.jpg
   2006/
      2006-10-13/
         20061013_431.jpg
         20061013_509.jpg
   2007/
      2007-01-30/
         20070130_002.jpg
         20070130_119-ew.jpg
      2007-04-19/
         20070419_bmd_323.jpg
         20070419_bmd_325-sd.jpg