Restore two column layout

Establishes basic functionality for viewing conversations in two column
mode, including message area and message list resizing, and maintaining
scroll position.

Various subviews need to be retooled but are more or less still
functional, i.e., new message, message detail, key verification, etc...

stylesheets/manifest.css

@@ -90,6 +90,7 @@ button.back {
   padding-right: 8px; }
   .menu .hamburger {
     width: 36px;
+    height: 36px;
     background: url("/images/menu.png") no-repeat center; }
   .menu .menu-list {
     display: none;
@@ -330,6 +331,7 @@ img.emoji {
 .gutter {
   padding: 36px 0 0; }
 
+.conversation-stack,
 .new-conversation, .inbox, .gutter {
   height: 100%; }
 
@@ -337,6 +339,10 @@ img.emoji {
   height: 100%;
   overflow: auto; }
 
+.gutter {
+  float: left;
+  max-width: 300px; }
+
 .socket-status {
   float: left;
   padding: 6px;
@@ -355,6 +361,25 @@ img.emoji {
   .socket-status .closed {
     background: url("/images/error_red.png") no-repeat left center; }
 
+.conversation-stack {
+  padding-left: 300px;
+  padding-top: 36px; }
+  .conversation-stack .conversation {
+    display: none; }
+  .conversation-stack .conversation:first-child {
+    display: block; }
+
+.conversation-header {
+  background: #f3f3f3; }
+
+.menu.conversation-menu {
+  float: right;
+  padding-left: 8px;
+  padding-right: 0; }
+  .menu.conversation-menu .menu-list {
+    right: 0;
+    left: initial; }
+
 .contact .number, .contact .checkbox {
   display: none; }
 
@@ -367,7 +392,7 @@ input.search {
 .fab {
   z-index: 1;
   position: fixed;
-  right: 25px;
+  left: 215px;
   bottom: 22px;
   height: 50px;
   width: 50px;
@@ -401,14 +426,14 @@ input.search {
 .index {
   color: #454545;
   background: #eee; }
-  .index .new-group-update-form {
+  .index .gutter .new-group-update-form {
     display: none;
     padding: 0.5em; }
   .index .last-message {
     margin: 6px 0;
     font-size: small;
     font-weight: 300; }
-  .index .timestamp {
+  .index .gutter .timestamp {
     position: absolute;
     top: 14px;
     right: 12px;
@@ -679,10 +704,7 @@ input.search {
     cursor: pointer; }
 
 .bottom-bar {
-  position: fixed;
-  bottom: 1px;
   height: 36px;
-  width: calc(100% - 2px);
   border-top: 1px solid #f3f3f3;
   background: white; }
   .bottom-bar button, .bottom-bar input, .bottom-bar textarea {