Fix tab order for reply, new post, new PM and PM reply forms.

newreply.tpl

find:
<input type="button" name="preview" value="{$lang.DO_PREVIEW}" class="form-button" onclick="doPreview();" />

change into
<input type="button" tabindex="4" name="preview" value="{$lang.DO_PREVIEW}" class="form-button" onclick="doPreview();" />

sendprivate.tpl 

Find
<input type="button" name="preview" value="{$lang.MESS_PREVIEW}" class="form-button" onclick="doPreview();" />

Change into
<input tabindex="4" type="button" name="preview" value="{$lang.MESS_PREVIEW}" class="form-button" onclick="doPreview();" />

mess_handler.tpl 

Find
<input type="submit" name="buttsubmit" value="{$lang.BUTT_SUBMIT}" class="form-button" />
<input type="button" name="preview" value="{$lang.PREVIEW}" class="form-button" onclick="doPreview();" />

Change into
<input tabindex="3" type="submit" name="buttsubmit" value="{$lang.BUTT_SUBMIT}" class="form-button" />
<input tabindex="4" type="button" name="preview" value="{$lang.PREVIEW}" class="form-button" onclick="doPreview();" />


newpost.tpl 

Find
<input type="button" name="preview" value="{$lang.DO_PREVIEW}" class="form-button" onclick="doPreview();"/>

Change into
<input type="button" tabindex="4" name="preview" value="{$lang.DO_PREVIEW}" class="form-button" onclick="doPreview();"/>