/**
@fn obj::move_slow_penalty
@section Use
<table>
	<tr>
		<th>Type(s)</th>
		<th>Description</th>
	</tr>	<tr>
		<td>
@ref page_type_211, @ref page_type_67, @ref page_type_88
		</td><td>    If &lt;slow movement&gt; is set to a value greater zero, all
    creatures moving over this spot will be slower than normal.

    &lt;slow movement&gt; 1  - rough terrain
    &lt;slow movement&gt; 2  - very rough terrain
    ...
    &lt;slow movement&gt; 7  - spider web (sticky as hell)</td>
	</tr>
	<tr>
		<td>
@ref page_type_138
		</td><td>    If &lt;slow movement&gt; is set to a value greater zero, all
    creatures moving over this spot will be slower than normal.

    &lt;slow movement&gt; 1  - rough terrain
    &lt;slow movement&gt; 2  - very rough terrain
    ...
    &lt;slow movement&gt; 5  - default for deep swamp</td>
	</tr>

*/