Replace gifs with pngs

* Smaller file size
* Use a uniform image format for logos/buttons across the site

logos/Makefile

@@ -1,3 +1,3 @@
-FILES = acm_logo.gif csc_logo.gif csc_only.png csc_title.gif uw_logo.gif
+FILES = acm_logo.png csc_logo.png csc_only.png csc_title.png uw_logo.png
 RELDIR = logos/
 include ../common.mk

xsl/common.xsl

@@ -39,15 +39,15 @@
 <xsl:template match="biglogo">
   <div class="biglogo">
     <div class="uwlogo">
-      <a href="http://www.uwaterloo.ca/"><img src="{$g_pre}logos/uw_logo.gif"
+      <a href="http://www.uwaterloo.ca/"><img src="{$g_pre}logos/uw_logo.png"
           alt="University of Waterloo" width="105" height="70" /></a>
     </div>
     <div class="acmlogo">
-      <a href="http://www.acm.org"><img src="{$g_pre}logos/acm_logo.gif"
+      <a href="http://www.acm.org"><img src="{$g_pre}logos/acm_logo.png"
            alt="A Student Chapter of the ACM" width="82" height="88" /></a>
     </div>
     <div class="csclogo">
-      <a href="{$g_pre}"><img src="{$g_pre}logos/csc_logo.gif"
+      <a href="{$g_pre}"><img src="{$g_pre}logos/csc_logo.png"
           alt="Computer Science Club" width="420" height="79" /></a>
     </div>
   </div>
@@ -65,7 +65,7 @@
   <xsl:param name="title" />
   <xsl:param name="href" />
   <div class="webtitle">
-    <a href="{$g_pre}"><img src="{$g_pre}logos/csc_title.gif"
+    <a href="{$g_pre}"><img src="{$g_pre}logos/csc_title.png"
         alt="CSC Logo" /></a>
   </div>
   <div class="dirheader">