fix in-call chat view

Chat view for text messaging during call wasn't working at all due to
multiple problems that are now fixed:
 - Conversation model in chat view wasn't set at all when call is set.
 - NSTableView is used instead of previous NSOutlineView like what is
   done in off-call conversation view.
 - Chat button is now displayed during call.

Moreover, sendMessage: in ConversationVC was getting the conversation
UID in a not-very-clever way. It is also fixed.

Change-Id: Iac406a62541abeed9817209e76082c74030162e6
diff --git a/ui/Base.lproj/CurrentCall.xib b/ui/Base.lproj/CurrentCall.xib
index 655fa8b..5b3cade 100644
--- a/ui/Base.lproj/CurrentCall.xib
+++ b/ui/Base.lproj/CurrentCall.xib
@@ -682,7 +682,7 @@
                                         <rect key="frame" x="0.0" y="0.0" width="372" height="465"/>
                                         <autoresizingMask key="autoresizingMask" widthSizable="YES" heightSizable="YES"/>
                                         <subviews>
-                                            <outlineView verticalHuggingPriority="750" allowsExpansionToolTips="YES" columnAutoresizingStyle="lastColumnOnly" selectionHighlightStyle="none" autosaveColumns="NO" rowHeight="60" rowSizeStyle="automatic" viewBased="YES" indentationPerLevel="16" outlineTableColumn="nFu-qN-GHK" id="ZOj-5b-rnp">
+                                            <tableView verticalHuggingPriority="750" allowsExpansionToolTips="YES" columnAutoresizingStyle="lastColumnOnly" selectionHighlightStyle="none" autosaveColumns="NO" rowHeight="60" rowSizeStyle="automatic" viewBased="YES" id="ZOj-5b-rnp">
                                                 <rect key="frame" x="0.0" y="0.0" width="372" height="465"/>
                                                 <autoresizingMask key="autoresizingMask"/>
                                                 <size key="intercellSpacing" width="3" height="2"/>
@@ -786,9 +786,10 @@
                                                     </tableColumn>
                                                 </tableColumns>
                                                 <connections>
+                                                    <outlet property="dataSource" destination="loh-bZ-dDU" id="G8m-dx-6OM"/>
                                                     <outlet property="delegate" destination="loh-bZ-dDU" id="TuS-js-CeK"/>
                                                 </connections>
-                                            </outlineView>
+                                            </tableView>
                                         </subviews>
                                     </clipView>
                                     <scroller key="horizontalScroller" hidden="YES" verticalHuggingPriority="750" horizontal="YES" id="zPy-Iz-oF9">