Bug 6709 - marc21_field_006.xml and marc21_field_008.xml can't be translated

Bug 6709 - marc21_field_006.xml and marc21_field_008.xml can't be translated

This patch changes
1) structure and schema for xml files used in MARC21
006 and 008 value builders.
2) JavaScript functions used to show value builders.

Xml processing is enabled in previous patch

Any translatable string has been moved to an xml element,
those strings that no need translation remains as xml
attributes.

NOTE_1: I do not include as translatable material types
codes, because those values are restricted in schema
definition. But this restriction can be removed.

NOTE_2: Anyone with experience in XML/XSD please
check the new schema definition.

NOTE_3: Anyone with experience in the former and
JavaScript please check xmlControlfield.js

To test:
1) Apply the patch
2) Verify that 006 and 008 value builders show and work
properly
3) Update translation files for your favorite language,
a new set of strings must show up corresponding to
names and descriptions on value builders.

Note: messed up patches, sending again.
Signed-off-by: Katrin Fischer <Katrin.Fischer.83@web.de>
All tests and QA script pass.

Did regression tests on the plugins for 006 and 008 and could
spot no differences in behavior of the plugins to before.

Also tested the translation process and found it working nicely.
Thank you for fixing this long standing translation bug!