High-level overview of changes to Perspectives

Format:
+ new feature
* bug or behavior fix


4.3.1
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* extract hardcoded strings and move to localization files
+ add (de), (es), and (fr) localizations! Many thanks to our translators.
+ fill in the missing strings from (zh-CN) localization. Many more thanks to our translators.
* clean up build process and tests
* fix SeaMonkey initialization; extension did not load


4.3
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* remove the forced statusbar icon (GH 38)
+ add Perspectives icons to alt-tab window
+ display key age in the notary results dialog
* UI improvements:
    * dialogs now center themselves in the screen
    + 'esc' cancels and closes dialogs
    * add cancel button to Preferences dialog
    * OK and Cancel buttons have a consistent placement
    * increase size of notary key textboxes to improve readability
    + alert popups now mention that they are from Perspectives
* don't throw exceptions when trying to add invalid URIs to the whitelist
* don't automatically close the 'report attack' window after an error (part of GH 49)
* add min and max boundary checking for quorum duration and quorum percentage (GH 52)
* fix parameter order for find_oldest_most_recent() (GH 48)
+ ignore blank lines when parsing notaries (GH 42)
* merge duplicate help pages, copyedit content, and update links
* add .css stylesheet for help pages; add some basic format/coloring
