UtilityClass: add a seconds() helper

This is intended to replace all those ugly magic frame numbers with
ever so slightly less ugly magic second numbers.

Basically, instead of saying:

    150 /* 5 seconds */

we can now say

    seconds(5)

desktop_version/src/UtilityClass.cpp

@@ -55,6 +55,11 @@ const char *GCChar(SDL_GameControllerButton button)
 	return NULL;
 }
 
+int seconds(const int s)
+{
+	return s * 30;
+}
+
 int ss_toi( std::string _s )
 {
 	std::istringstream i(_s);

desktop_version/src/UtilityClass.h

@@ -5,6 +5,8 @@
 #include <vector>
 #include <string>
 
+int seconds(const int s);
+
 int ss_toi(std::string _s);
 
 std::vector<std::string> split(const std::string &s, char delim, std::vector<std::string> &elems);