Fix stack balancing problems by refactoring execution calls

- Con::executef now uses a template
- All public execution functions now restore the console stack upon return
- Fixed bad parameters on some callbacks
- Reverts get*Arg behavior

Engine/source/console/stringStack.h

@@ -127,6 +127,7 @@ struct StringStack
    /// Return a temporary buffer we can use to return data.
    char* getReturnBuffer(U32 size)
    {
+      AssertFatal(Con::isMainThread(), "Manipulating return buffer from a secondary thread!");
       validateArgBufferSize(size);
       return mArgBuffer;
    }
@@ -136,6 +137,7 @@ struct StringStack
    /// This updates the function offset.
    char *getArgBuffer(U32 size)
    {
+      AssertFatal(Con::isMainThread(), "Manipulating console arg buffer from a secondary thread!");
       validateBufferSize(mStart + mFunctionOffset + size);
       char *ret = mBuffer + mStart + mFunctionOffset;
       mFunctionOffset += size;
@@ -314,6 +316,8 @@ public:
 
    void pushVar(ConsoleValue *variable);
    void pushValue(ConsoleValue &value);
+   ConsoleValue* reserveValues(U32 numValues);
+   bool reserveValues(U32 numValues, ConsoleValueRef *values);
    ConsoleValue* pop();
 
    ConsoleValue *pushString(const char *value);
@@ -338,4 +342,7 @@ public:
    ConsoleValueRef mArgv[MaxArgs];
 };
 
+extern StringStack STR;
+extern ConsoleValueStack CSTK;
+
 #endif