Several examples trim their buffer with an extra LWS_PRE from the end...
actually end should point to end the end of buf without a second LWS_PRE
reservation.
https://github.com/warmcat/libwebsockets/issues/2629
Added the ability to get additional form parameters with unknown names in the form parameters parser lws_spa. The example of using the form parameters parser has been updated. Fixed bug of double freeing memory in the example.