Allow compilePhonemeData and compileIntonations to be called with a NULL log argument

Stop leaking file streams in libespeak-ng's LoadSpectSeq function.

The code portability will be provided through the autotools build
system. Any additional portability code will be provided in the
top-level source structure along side the other code (e.g. `src/compat`).

This creates an fread compatible API on wxInputStream objects and
uses that API in LoadSpectSeq. This is to help the transition from
the wxWidgets wxInputStream API to the C FILE API.

This removes the GUI part of espeakedit, keeping the part that is
responsible for compiling the voice and intonation data. The
motivation for this is:

  1.  the voice and intonation data compilation will move into
      libespeak-ng after removing the wxWidgets logic and converting
      the code to C;

  2.  the espeakedit code is tightly coupled to the internals of
      libespeak-ng at a source code level, not a binary/API level,
      making the code harder to maintain;

  3.  a new GUI will be written in Qt that better supports creating
      and editing voices and languages.