hg log: Move filtering implicit parents to own method and use it in templater.
Extended test repo in test-command-template to contain changeset to test this.
#header#
<title>#repo|escape#: searching for #query|escape#</title>
</head>
<body>
<div class="buttons">
<a href="#url#log{sessionvars%urlparameter}">changelog</a>
<a href="#url#shortlog{sessionvars%urlparameter}">shortlog</a>
<a href="#url#tags{sessionvars%urlparameter}">tags</a>
<a href="#url#file/#node|short#{sessionvars%urlparameter}">manifest</a>
#archives%archiveentry#
</div>
<h2>searching for #query|escape#</h2>
<form>
{sessionvars%hiddenformentry}
<p>
search:
<input name="rev" type="text" width="30" value="#query|escape#">
</p>
</form>
#entries#
<form>
{sessionvars%hiddenformentry}
<p>
search:
<input name="rev" type="text" width="30" value="#query|escape#">
</p>
</form>
#footer#