Update Unihan_Variants.txt from “2013-02-25 Unicode 6.3.0” to “2014-05-09 Unicode 7.0.0”

And regenerate engine/chinese_variants.py.

New lines in Unihan_Variants.txt which are relevant for simplified and
traditional detection:

> U+9FC1	kSimplifiedVariant	U+4724
> U+4724	kTraditionalVariant	U+9FC1

U+4724 = 䜤 U+9FC1 = 鿁
Apply fix for 同 again to Unihan_Variants.txt, it is both simplified *and* traditional Chinese

This fix is not yet included in Unicode 7.0.0. It will be included
in a future version though.
Fix typo in comment
Move the “Restore all defaults” button into the GtkButtonBox at bottom

- Makes the dialog a little bit less tall (helps for small screens)
- I want to add another tab for detailed settings, the “Restore all defaults”
  button restores the defaults for all options in all tabs, therefore it
  should not be part of a tab.
Update German translation
Update Chinese .po files
Use the “notify::text” signal instead of “activate” on GtkEntry widget

To make it possible that any change of text in the GtkEntry widgets
is applied immediately. The “activate” signal is only emitted
when Enter/Return is typed, the “notify::text” signal is emitted
on any sort of change in the text.
Release v1.8.7