strip leading/trailing whitespace

[xflr6]

String columns where trim(column) != column:

        table                  column  trims
0      source                  author    340
1      source                    name    338
2         ref  normalizedauthorstring     65
3      source                  editor      7
4         ref  normalizededitorstring      3
5   macroarea             description      2
6  identifier                    name      1
7    language                    name      1
8    provider                    name      1

Fix reference author, editor, and name (also) in the sources (or the merge script)?