Move ugly _POSIX_SOURCE and _POSIX_C_SOURCE=200112L flags to pipe_posix.c.

They are only needed for popen and pclose, so let's define them just
in the one file that uses popen and pclose. This way it's obvious why
we need to define them (because stupid GNU requires them for the
*standardized* popen and pclose calls).
Merge pull request #88 from eaburns/dev/eaburns

Move ugly _POSIX_SOURCE and _POSIX_C_SOURCE=200112L flags to pipe_posix.c
UNAME variable serves no purpose
Merge pull request #91 from mccoyst/master

UNAME variable serves no purpose
Describe how to run it

Work for #17.
Merge pull request #92 from mccoyst/readme

Describe how to run it
Plaintext formatting
Add debugging details

Work for #17.
Fix the worst spelling error of all time
Make the knight look mildly less Gumbylike
First try at new knight's sheet

Man, the whole sword thing needs to be reworked
Eliminate per-part armor images
Play with doors

Work for #66
Simplify "normal" water
Try flat bricks
Try flat walls?
Start scaling graphics.
Flatten unti.
Flatten heart.
Mess with the shrine.