hgmerge: fix diff+patch detection; cleanups
Details:
- actually show help message when no tools are found
- whitespace cleanup (stupid emacs)
- quote more variables
- simplify merge/diff3 error handling
#header#
<title>Mercurial repositories index</title>
</head>
<body>
<h2>Mercurial Repositories</h2>
<table>
<tr>
<td>Name</td>
<td>Description</td>
<td>Contact</td>
<td>Last change</td>
<td> </td>
<tr>
#entries%indexentry#
</table>
#footer#