Simplified file paths

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rename : chrome/content/transliterator/layout-viewer.js => chrome/content/layout-viewer.js
rename : chrome/content/transliterator/layout-viewer.xul => chrome/content/layout-viewer.xul
rename : chrome/content/transliterator/prefs.js => chrome/content/prefs.js
rename : chrome/content/transliterator/prefs.xul => chrome/content/prefs.xul
Made sure Add-ons Manager will still show extension icon even if the extension is disabled

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rename : chrome/skin/tocyrillic.png => icon.png