handbook: trademarks and copyright

- add 2015 as a year we've edited the handbook
	- remove 'maple', 'U.S. Robotics' and 'Sound Blaster' as we no
	  longer reference those trademarks.

en_US.ISO8859-1/books/handbook/book.xml

@@ -49,6 +49,7 @@
       <year>2012</year>
       <year>2013</year>
       <year>2014</year>
+      <year>2015</year>
       <holder>The FreeBSD Documentation Project</holder>
     </copyright>
 
@@ -62,7 +63,6 @@
       &tm-attrib.adaptec;
       &tm-attrib.adobe;
       &tm-attrib.apple;
-      &tm-attrib.creative;
       &tm-attrib.google;
       &tm-attrib.heidelberger;
       &tm-attrib.ibm;
@@ -79,9 +79,7 @@
       &tm-attrib.sun;
       &tm-attrib.themathworks;
       &tm-attrib.thomson;
-      &tm-attrib.usrobotics;
       &tm-attrib.vmware;
-      &tm-attrib.waterloomaple;
       &tm-attrib.wolframresearch;
       &tm-attrib.xfree86;
       &tm-attrib.xiph;