Fix bug with two or more wires connected to one input. Now only one wire can be connected to one input, except BOOLean signals in LD and SFC. If user trying to connect wire with already connected input, wire highlight will become red.
Signed-off-by: Andrey Skvortsov <andrej.skvortzov@gmail.com>

int CheckRetainBuffer(void)
{
	return 1;
}

void ValidateRetainBuffer(void)
{
}

void InValidateRetainBuffer(void)
{
}

void Retain(unsigned int offset, unsigned int count, void *p)
{
}

void Remind(unsigned int offset, unsigned int count, void *p)
{
}