Add audible captcha support to pastiche

This requires espeak in addition to figlet and will generate an audio
tag or a link to the wav file if the browser does not support the
audio tag. Tested with Firefox and lynx.
Make espeak pause between characters

This makes the a in "bar" audible again.
Fix layout of form

This makes the audio tag / audio link align nicely with the rest
again.
Make audible captchas configurable

audible-captcha? is a new parameter that will enable audible
captchas. The default is #t.

Also bail out on bogus input parameters or unkown hashes for captchas.
Make audio download link unconditionally rendered

If there are browsers that support the audio tag but someone still has
trouble figuring it out maybe the direct link is of more help.
Add space between strings to be concatenated

Without those spaces, the output would be:

  ... figletdoesn't...
  ... espeakdoesn't...
fix tool-installed?

Previously it always returned a truthy value (a procedure). Now
it properly returns a boolean.

It has been internally restructured to search for the given filename
in PATH, since the `-v' trick is not valid anymore (espeak's `-v'
requires an argument).
Remove useless code, spotted by Mario
Pronounce the captcha based on the provided language preference.

This should make it easier to understand as the letters are spelled
with the "correct accent".
Merge branch 'audible-captchas'
Bump version to 0.19