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Rewrite testcases for error handler

Now they actually test desired behaviour, not random side effects of the
code.
Fix class documentation
Wrap long lines
Merge pull request #154 from lem9/master

Notice about missing non-unique column
Update po files
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When referring to a table, we use the term "column"
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Merge remote-tracking branch 'origin/master'
Update po files
Merge remote-tracking branch 'origin/master'
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Fix - Bugs:#3802 Datepicker displayed just the first time

Fixed the bug that was preventing the datepicker from displaying after
ajax call. datepicker remained initialized while its content was
replaced by the ajax response. tbl_change.js now reinitializes
datepicker everytime its loaded.
Fix a bug: when doing a db search, then clicking on Browse on a result
row, the query generated for (at least) the Delete link was missing the
table name.
Forgot to fix the test