avoid too large regexes, try to fix #199

Let the token type scheme.Word decide on instantiation which token type
really to instantiat, by looking at the word lists, instead of creating
the regexes directly from the (long) word lists.
Revert "avoid too large regexes, try to fix #199"
I was too quick, the state.follow() stuff could break subtly by this.

This reverts commit 502e347c6a2be5b183a655dfcbed84fc4896b664.
multiple Token classes in Parser may have same regexp

It is now possible for multiple token types in a Parsers items list to have
the same rx attribute. In this case the token type test_match() method is
called for all but the last one in the list. The first one returning true is
used.
use the new possibility in slexer for multiple token types to have the same rx and use test_match() to distinghuish token type based on word lists, avoiding too long regexps.
add inf and nan to scheme number
typo nl.po
better number matching for scheme
improve slexer documentation
Remove invalid headers from PO files. Fixes #200.
stub for settings version upgrade.

what needs to be done:
- use new and correct domain name in app.py
- implement the settings transfer in install/update.py
- when that works well, uncomment the two lines in install/__init__.py
settings upgrade

- use new and correct domain name in app.py
- implement the settings transfer in install/update.py
settings version upgrade

uncommented the two lines in install/__init__.py
solve problem with QSettings when calling session.py directly

the organization name and domain and the application name must be set
before calling QSettings()
Merge pull request #202 from dliessi/settings-version-1

complete the settings upgrade to version 1
Merge pull request #201 from dliessi/issue200

Remove invalid headers from PO files. Fixes #200.
regenerate lilypond data with 2.16.2
Merge branch 'master' of github.com:wbsoft/frescobaldi
preview-mode: Add debug-layout-options.ly base file

Main file that includes the individual debug modes.
Included as -dinclude-settings.
preview-mode: Initial infrastructure in command.py

When composing a command as preview compilation
add several items to it.
preview-mode: Add color-voices mode file

color voices explicitly set