gitweb: preserve whitespace in description

Without this, multiple spaces or tabs in the commit message aren't
preserved and things like tables don't align properly.

As part of adding the CSS rule, we had to cuddle the content
with the <div> to not introduce leading and trailing whitespace.
The "addbreaks" filter was also removed because it would insert
an additional newline, effectively double spacing content.

Differential Revision: https://phab.mercurial-scm.org/D113

mercurial/templates/gitweb/changelogentry.tmpl

@@ -7,8 +7,6 b''
 </div>
 <i>{author|obfuscate} [{date|rfc822date}] rev {rev}</i><br/>
 </div>
-<div class="log_body description">
-{desc|strip|escape|websub|addbreaks|nonempty}
-<br/>
-<br/>
+<div class="log_body description">{desc|strip|escape|websub|nonempty}
+
 </div>

mercurial/templates/gitweb/changeset.tmpl

@@ -45,9 +45,7 b' changeset |'
 {child%changesetchild}
 </table></div>
 
-<div class="page_body description">
-{desc|strip|escape|websub|addbreaks|nonempty}
-</div>
+<div class="page_body description">{desc|strip|escape|websub|nonempty}</div>
 <div class="list_head"></div>
 <div class="title_text">
 <table cellspacing="0">

mercurial/templates/gitweb/fileannotate.tmpl

@@ -61,9 +61,7 b' annotate |'
 </table>
 </div>
 
-<div class="page_path description">
-{desc|strip|escape|websub|addbreaks|nonempty}
-</div>
+<div class="page_path description">{desc|strip|escape|websub|nonempty}</div>
 <div class="page_body">
 <table>
 <tbody class="sourcelines"

mercurial/templates/gitweb/filerevision.tmpl

@@ -61,9 +61,7 b' file |'
 </table>
 </div>
 
-<div class="page_path description">
-{desc|strip|escape|websub|addbreaks|nonempty}
-</div>
+<div class="page_path description">{desc|strip|escape|websub|nonempty}</div>
 
 <div class="page_body">
 <pre class="sourcelines stripes"

mercurial/templates/static/style-gitweb.css

@@ -175,6 +175,7 b' pre.sourcelines.stripes > span:target {'
 
 .description {
     font-family: monospace;
+    white-space: pre;
 }
 
 /* Followlines */

tests/test-hgweb.t

@@ -340,7 +340,7 b' static file'
 
   $ get-with-headers.py --twice localhost:$HGPORT 'static/style-gitweb.css' - date etag server
   200 Script output follows
-  content-length: 8985
+  content-length: 9007
   content-type: text/css
   
   body { font-family: sans-serif; font-size: 12px; border:solid #d9d8d1; border-width:1px; margin:10px; background: white; color: black; }
@@ -520,6 +520,7 b' static file'
   
   .description {
       font-family: monospace;
+      white-space: pre;
   }
   
   /* Followlines */