* Simplify some constructs from the Python-3 migration
* update copyright, since I did maintain the SCons build continuosly
* remove unused method from Buildhelper
Furthermore, the documentation page for our build system
https://lumiera.org/documentation/technical/build/SCons.html
has been reworked, to add a synopsis, some further background
information about the internal structure of SCons and about
the specific conventions and definitions used for Lumiera
Mostly, std::regexp can be used as a drop-in replacement.
Note: unfortunately ECMA regexps do not support lookbehind assertions.
This lookbehind is necesary here because we want to allow parsing values
from strings with additional content, which means we need explicitly to
exclude mismatches due to invalid syntax.
We can work around that issue like "either line start, or *not* one of these characters.
Alternatively we could consider to make the match more rigid,
i.e we would require the string to conain *only* the timecode spec to be parsed.
