Refactor documentation.

- Create morphodita_about containing basic information about MorphoDiTa.
  This is used in README, beginning of MorphoDiTa manual, on MorphoDiTa
  demo page and LINDAT/CLARIN pages.

- Create morphodita_readme using morphodita_about.

- Add support for underlining headers in txt formats. The underline must
  be present directly in .t2t file, it is removed in Makefile in the
  html targets.
Ignore generated .txt and .html files.
Rephrase the description of UFAL website.

The real site that hosts the tool and the models will be LINDAT/CLARIN,
nevertheless, ufal.mff.cuni.cz/morphodita is the main website for the
tool.
Offer the C++ library in the pre-build packages.
Remove the arch-specific sources.

They were used only to lower the version requirements of the libc.

Currently they are used only internally when building binary packages.
Move the model documentation to separate file.

This way, we can create documentation for the package containing only
the specific language model. To that end, morphodita_model_about and
morphodita_model_czech_readme are provided.
Elaborate on three-part lemma structure.
Add documentation to raw lemmas variants.
Update compiled documentation.
Fix wrong line breaking splitting a reference.
Add required MorphoDiTa version and latest model version.
Slightly simplify Makefile rules.
Add underlines to all t2t files except morphodita.t2t.
Fix typo.
Remove forgotten paragraph.
Use correct MorfFlex permalink, add info about guessers.
Move emergency sentence splitting to utf8_tokenizer.
Move prefixes with hyphen to separate automatically generated file.
Recognize also ([Ee] [+-]? \d+)? number suffix.

This number suffix is recognized by the tokenizer, so for consistency we
recognize it during morphologic analysis too.
Merge branch 'master' of redmine:morphodita