fdo#82860 RTF export: don't export textboxes of shapes twice

See 96965fb39d6d376e91030a01c11f16f9428ddf2e (DOCX drawingML export:
don't export textboxes of shapes twice, 2014-06-06).

Change-Id: I89c039debeca5f88f172479b9f8ecbaec2dc7bc4
fdo#82860 RTF export: if shape has textbox, export its contents as shape text

See 8c677716c4707ccd86b152ae504841affb393cc0 (DOCX drawingML export: if
shape has textbox, export its contents as shape text, 2014-06-06).

Change-Id: I5b1afae4d1b80c9b225096677f7d7ae77ff90f5b
fdo#82860 RTF import: fix handling of SHAPE fields

No need to use fieldmarks for these.

Change-Id: I8d2c797f2b00be88e445dab0dd69cb1a9556c02c