Interpret multiple regular expression terms in a regular expression operator as alternatives in C2

[Akron]

First fix #66!

C2 supports a list of regular expressions inside the regular expression operator #REG(...) that are interpreted as alternatives.

At the moment KorAP interprets #REG(Bal.?m Wau.*) as a sequence of /Bal.?m/ and /Wau.*/ (see #63 regarding wrong placeholder interpretation). The correct interpretation would be either an or-group or the joined regex /(?:Bal.?m)|(?:Wau.*)/.

[Akron]

The first interpretation with an or-group seems to be preferable and technical closer to C2s implementation. The advantage is that intermediate interpretations such as Glemm are able to interpret these regular expressions separately.