Make bw_trace_reset_status() more context sensitive

[bobbingwide]

bw_trace_reset_status() determines whether or not the trace file needs to be reset based on a number of values.

When debugging my WooCommerce shipping plugin I found I had to configure trace reset to not reset the trace file every transaction since the Cart display was immediately followed by wc-ajax=get_refreshed_fragments.

Altering bw_trace_reset_status() to not reset when the $_REQUEST contained 'wc-ajax' was a pragmatic solution to the trace reset problem.

I think the solution should should be generalised. e.g. The AJAX heartbeat request may be another example where you don't want (AJAX) tracing to be reset.

[bobbingwide]

With the changes for #71 this solution is no longer necessary. You can set the Trace file generation limit, so that each transaction's output is traced to a different file. It doesn't make sense to set the value to a small number like 1 or 2.

[bobbingwide]

This wasn’t closed in v3.0.0. Moving to 3.1.0. Need to remove logic that responds to a reset parameter being passed in the URL. It’s no longer necessary.