Added tooltip option

Tooltips should be entered in the 'tooltip' field of each tab tiddler

core/wiki/macros/tabs.tid

@@ -5,13 +5,15 @@ tags: $:/tags/Macro
 <div class="tc-tab-set $class$">
 <div class="tc-tab-buttons $class$">
 <$list filter="$tabsList$" variable="currentTab">
-<$button set=<<qualify "$state$">> setTo=<<currentTab>> default="$default$" selectedClass="tc-tab-selected">
+<$tiddler tiddler=<<currentTab>> >
+<$button set=<<qualify "$state$">> setTo=<<currentTab>> default="$default$" selectedClass="tc-tab-selected" tooltip={{!!tooltip}}>
 <$set name="tv-wikilinks" value="no">
 <$transclude tiddler=<<currentTab>> field="caption">
 <$macrocall $name="currentTab" $type="text/plain" $output="text/plain"/>
 </$transclude>
 </$set>
 </$button>
+</$tiddler>
 </$list>
 </div><div class="tc-tab-divider $class$"/><div class="tc-tab-content $class$">
 <$list filter="$tabsList$" variable="currentTab">