doc additions

[Werner]

> Am I top posting?

1.
In the glossary should be given the words hook and pennant beside flag (1.128).
Pennant (1.223) has a link to flag (1.128), hook unfortunately doesn't exist,
please create like pennant.

2.
Searching the glossary file for „Fähnchen“ doesn't find this word. Maybe it is
made with e composed "a instead of an ä? 

3.
In the Notation Reference, maybe there should be added two things in 
1.3.2 Slurs, 
first: that \slurDown, \slurUp will take affect on all following slurs,
second: that _( will make only this slur beeing downwards and ^( upwards.