qt: Periodic translations update

Update English translation from source code, and pull other translations
from Transifex.

src/qt/bitcoinstrings.cpp

@@ -181,6 +181,7 @@ QT_TRANSLATE_NOOP("bitcoin-core", "Generate coins (default: 0)"),
 QT_TRANSLATE_NOOP("bitcoin-core", "Get help for a command"),
 QT_TRANSLATE_NOOP("bitcoin-core", "How many blocks to check at startup (default: 288, 0 = all)"),
 QT_TRANSLATE_NOOP("bitcoin-core", "If <category> is not supplied, output all debugging information."),
+QT_TRANSLATE_NOOP("bitcoin-core", "Importing..."),
 QT_TRANSLATE_NOOP("bitcoin-core", "Imports blocks from external blk000??.dat file"),
 QT_TRANSLATE_NOOP("bitcoin-core", "Incorrect or no genesis block found. Wrong datadir for network?"),
 QT_TRANSLATE_NOOP("bitcoin-core", "Information"),