Support Continuous Auto-Detection.

[MS-RDPBCGR] 3.2.5.14 Network Characteristics Detection

When receiving a Bandwidth Measure Start (section 2.2.14.1.2):
If the requestType field equals 0x0014:
...
<b>When receiving any data from the server, add the number of bytes received to the Network Characteristics Byte Count store</b> (section 3.2.1.17).