Merge bitcoin-core/gui#21: Update pruning tooltip, original author BitcoinErrorLog

2fc5efc Update pruning tooltip, original author BitcoinErrorLog (Riccardo Spagni)

Pull request description:

  Squashed commits from BitcoinErrorLog at his request, per the original discussion on #15: this tooltip has been adjusted to be more user-friendly and reflect what the net effect of pruning is for the user.

ACKs for top commit:
  harding:
    Untested ACK 2fc5efc
  Sjors:
    utACK 2fc5efc and welcome to the dark side!
  jonasschnelli:
    ACK 2fc5efc

Tree-SHA512: 45d6a7efbf4d34d20b9de439c988a39c739591b854726b6682c4cffcb23dff7d9131afab572fa0c9a8bc033c46c3878efdfbf8a984aafde632e1dfc1caa1cbbb

Author: jonasschnelli

src/qt/forms/optionsdialog.ui

@@ -164,7 +164,7 @@
         <item>
          <widget class="QCheckBox" name="prune">
           <property name="toolTip">
-           <string>Disables some advanced features but all blocks will still be fully validated. Reverting this setting requires re-downloading the entire blockchain. Actual disk usage may be somewhat higher.</string>
+           <string>Enabling pruning significantly reduces the disk space required to store transactions. All blocks are still fully validated. Reverting this setting requires re-downloading the entire blockchain.</string>
           </property>
           <property name="text">
            <string>Prune &amp;block storage to</string>