FMSLogo Code

Fix Bug #511; Fix the Spanish translations for READPOS and WRITEPOS (as
POSLECTURA and POSESCRITURA, respectively).

Standardize on "archivo" as the translation for "file", not "fichero".
This is what Wikipedia uses and is what Daniel Ajoy used in all of the
text messages.

Translate the documentation for the Receptors to Spanish.
This was based on the translation of MSWLogo's manual by Rosario Ruiz.

Fix a typo: "the the" -> "that the"

Translate the "Transmitters" section of the Communications chapter into Spanish.
The translation was based on Rosario Ruiz's translation of the MSWLogo manual.

Translate the "data structure queries" section to Spanish.
This was based on Rosario Ruiz's translation of the MSWLogo manual.

Terminology standardization: "has" -> "outputs"

Fix the part about CASEIGNOREDP so that it explains how to
use it to change the behavior of EQUALP (the documentation only
explained what it meant if it were "TRUE, which is also the
default behavior and applies equally to any variable).

Split the documentation for equality into separate paragraphs,
one for each primitive type. This makes it more readable.

Also clarify that lists are only equal of the like members are
in the same order.

Reorder the paragraphs in the documentation for SUBSTRINGP so that
the common case (use on words) is listed first. Documentating that
it outputs false for arrays and lists is more for completeness than
usefulness.