enhance scripted time library a bit

1. Add __tostring functions for both the `l_Timestamp` and `l_TimeSpan` types
2. Add a `getSeconds` function for the `l_Timestamp` type

Author: Goober5000

code/scripting/api/objs/time_obj.cpp

@@ -1,11 +1,12 @@
 //
 //
 #include "time_obj.h"
+#include "globalincs/pstypes.h"
 
 namespace scripting {
 namespace api {
 
-ADE_OBJ(l_Timestamp, uint64_t, "timestamp", "A real time time stamp of unspecified precision and resolution.");
+ADE_OBJ(l_Timestamp, uint64_t, "timestamp", "A real-time timestamp of unspecified precision and resolution.");
 
 ADE_FUNC(__sub, l_Timestamp, "timestamp other", "Computes the difference between two timestamps", "timespan",
          "The time difference")
@@ -20,9 +21,44 @@ ADE_FUNC(__sub, l_Timestamp, "timestamp other", "Computes the difference between
 	return ade_set_args(L, "o", l_TimeSpan.Set(diff));
 }
 
+ADE_FUNC(__tostring, l_Timestamp, nullptr, "Converts a timestamp to a string", "string", "Timestamp as string, or empty string if handle is invalid")
+{
+	uint64_t value = 0;
+	if (!ade_get_args(L, "o", l_Timestamp.Get(&value)))
+		return ade_set_error(L, "s", "");
+
+	char buf[32];
+	sprintf(buf, UINT64_T_ARG, value);
+
+	return ade_set_args(L, "s", buf);
+}
+
+ADE_FUNC(getSeconds, l_Timestamp, nullptr, "Gets the value of this timestamp in seconds", "number", "The timestamp value in seconds")
+{
+	uint64_t value = 0;
+	if (!ade_get_args(L, "o", l_Timestamp.Get(&value)))
+		return ade_set_error(L, "f", 0.0f);
+
+	// Timestamps and spans are stored in nanoseconds
+	return ade_set_args(L, "f", static_cast<float>(static_cast<long double>(value) / static_cast<long double>(NANOSECONDS_PER_SECOND)));
+}
+
+
 ADE_OBJ(l_TimeSpan, int64_t, "timespan", "A difference between two time stamps");
 
-ADE_FUNC(getSeconds, l_TimeSpan, nullptr, "Gets the value of this timestamp in seconds", "number",
+ADE_FUNC(__tostring, l_TimeSpan, nullptr, "Converts a timespan to a string", "string", "Timespan as string, or empty string if handle is invalid")
+{
+	int64_t value = 0;
+	if (!ade_get_args(L, "o", l_TimeSpan.Get(&value)))
+		return ade_set_error(L, "s", "");
+
+	char buf[32];
+	sprintf(buf, INT64_T_ARG, value);
+
+	return ade_set_args(L, "s", buf);
+}
+
+ADE_FUNC(getSeconds, l_TimeSpan, nullptr, "Gets the value of this timespan in seconds", "number",
          "The timespan value in seconds")
 {
 	int64_t value = 0;
@@ -31,7 +67,7 @@ ADE_FUNC(getSeconds, l_TimeSpan, nullptr, "Gets the value of this timestamp in s
 	}
 
 	// Timestamps and spans are stored in nanoseconds
-	return ade_set_args(L, "f", (float)((long double)value / (long double)NANOSECONDS_PER_SECOND));
+	return ade_set_args(L, "f", static_cast<float>(static_cast<long double>(value) / static_cast<long double>(NANOSECONDS_PER_SECOND)));
 }
 
 } // namespace api