USB cameras connected to a windows PC take longer to start, which results in an exception when trying to access data that hasn't been initialized, causing the program to crash.

@sbow Had a USB camera connected to a laptop. After compiling the program it would crash on the first loop due to an exception being thrown about arrays being accessed out of bounds in the track_target.cpp file. A breakpoint showed that the issue occured at the line where the `target_height` was being determined. The solution for this was to add a small delay at the beginning of the program as shown below: ``` Video::in_loop(); if (first_loop_after_start) { std::this_thread::sleep_for(std::chrono::seconds(3)); } Detection::loop(); ``` This is a good temporary solution if this issue is being faced by anyone, but a long term solution is needed to avoid having a delay in the code. Maybe better checks to ensure that array indices are not out of range, or that data is only access after properly initialized and if available.