ADD: @pwpivi 's latest fixes for bigbuff

ADD:  @marshmellow 14b changes.

fix:  fixes to the timing inside iso14443b.c  sniff/sending.  Between TX & RX there should be a 151us pause.

armsrc/fpgaloader.c

@@ -436,6 +436,8 @@ void FpgaDownloadAndGo(int bitstream_version)
 	}
 
 	inflateEnd(&compressed_fpga_stream);
+	
+	BigBuf_free();
 }