Version must be changed in:
- configure.ac
- src/windows/config.h
- android/jni/include/config.h
- android/build.gradle
- android/AndroidManifest.xml

It's unclear why c2 needs to be set after an entity reference.

ProcessSsmlTag()

Note the line in readclause.c:
if ((c2 == '/') || iswalpha(c2) || c2 == '!' || c2 == '?') {

It might be enough to pass everything to ProcessSsmlTag. What are the
cases that are skipped because of this?

This is a bit slower since we don't pass n_xml_buf as an argument but
rather get it with a call to wcslen. It is much cleaner though, since
the name ProcessSsmlTag() implies that all processing should be done
there.

Creation of language definition file for Ido language.

Creation of "io_list" file for Ido language

Rules for initial support of Ido language.

Added initial support for Ido language (similar to Esperanto).

It's a duplicate of CTRL_EMBEDDED.

this_ph_data, N_WAV_BUF, option.device, harm_sqrt_n,  max_hval, next_pause

Going through files in src/libespeak-ng/, include-what-you-use removed a
few unnecessary includes and included explanations on why a certain
header should be included. This makes tracking globals and dependencies easier.

Running the codebase through IWYU should be repeated after each major
code restIncludes to standard c library weren't checked to avoid
breaking builds with other platforms.

See https://github.com/include-what-you-use/include-what-you-use