1) update the logos to svg
2) add svg icon for strict security policy where used
3) define new vhost option flag to enforce sending CSP headers
with the result code
4) add vhost option flag to minimal examples to
enforce sending CSP where applicable
5) Go through all the affecting examples confirming they
still work
6) add LWS_RECOMMENDED_MIN_HEADER_SPACE constant (currently
2048) to clarify when we need a buffer to hold headers...
with CSP the headers have become potentially a lot
larger.
This replaces the old test-app for echo with separate client and server
minimal versions.
The autobahn test script is made more autonomous and tests both
client and server.
