implement mime exceptions to "use desktop open" so that we can use evince and pass page and search string parameters for pdf,ps and dvi even when all other mime types are passed to xdg-open

src/utils/conftree.cpp

@@ -246,7 +246,7 @@ int ConfSimple::get(const string &nm, string &value, const string &sk) const
 // Appropriately output a subkey (nm=="") or variable line.
 // Splits long lines
 static ConfSimple::WalkerCode varprinter(void *f, const string &nm, 
-				      const string &value)
+					 const string &value)
 {
     ostream *output = (ostream *)f;
     if (nm.empty()) {
@@ -276,7 +276,8 @@ int ConfSimple::set(const std::string &nm, const std::string &value,
 {
     if (status  != STATUS_RW)
 	return 0;
-
+    LOGDEB2(("ConfSimple::set [%s]:[%s] -> [%s]\n", sk.c_str(),
+	     nm.c_str(), value.c_str()));
     if (!i_set(nm, value, sk))
 	return 0;
     return write();

src/utils/conftree.h

@@ -408,7 +408,8 @@ public:
     {
 	if (!m_ok)
 	    return 0;
-
+	//LOGDEB2(("ConfStack::set [%s]:[%s] -> [%s]\n", sk.c_str(),
+	//nm.c_str(), val.c_str()));
 	// Avoid adding unneeded entries: if the new value matches the
 	// one out from the deeper configs, erase or dont add it
 	// from/to the topmost file