fix possibly endless matchingDegree calculation (IDEA-126721)

* NameUtil.nextWord should always return a value greater than its argument
* There are neither lowercase nor uppercase unicode letters
* so check for !upperCase instead of lowerCase to ensure we traverse at least one letter
EA-57776 - NPE: JavaLanguageLevelPusher.pushLanguageLevel
PsiAnchor: check instanceof PsiFileImpl (EA-57767)
don't report velocity exceptions to EA (EA-57744, EA-57739 etc)
BaseCompleteMacro: be prepared to another completion being in progress in invokeLater (EA-57726)
completion: reset to initial state upon insert handler exceptions (EA-57472)
EA-57391 - SOE: JavaDocInfoGenerator.searchDocTagInSupers
NavigationItemListCellRenderer: don't render invalid elements (EA-56774)