Change some ints and chars to unsigned

Convert some of the int and char variables to be unsigned int and unsigned
char types.  This prevents gcc generating the warnings "comparison between
signed and unsigned integer expressions" and "array subscript has type
'char'", as well as having a nice side-effect of shaving 42 bytes off the
compiled size when building for the Uno.

WebServer.h

@@ -308,7 +308,7 @@ class WebServer: public Print
   const char *m_urlPrefix;
 
   unsigned char m_pushback[32];
-  char m_pushbackDepth;
+  unsigned char m_pushbackDepth;
 
   int m_contentLength;
   char m_authCredentials[51];
@@ -321,7 +321,7 @@ class WebServer: public Print
     const char *verb;
     Command *cmd;
   } m_commands[8];
-  char m_cmdCount;
+  unsigned char m_cmdCount;
   UrlPathCommand *m_urlPathCmd;
 
   void reset();
@@ -480,9 +480,9 @@ bool WebServer::dispatchCommand(ConnectionType requestType, char *verb,
   // if the first character is a slash,  there's more after it.
   if (verb[0] == '/')
   {
-    char i;
+    unsigned char i;
     char *qm_loc;
-    int verb_len;
+    unsigned int verb_len;
     int qm_offset;
     // Skip over the leading "/",  because it makes the code more
     // efficient and easier to understand.