Fixed showing TOS floater.

This creates a separate events interface structure
for CurlResponderBuffer (AICurlResponderBufferEvents)
for dealing with received HTTP headers.

The headers are passed to the Responder, but only
if the class derived from Responder implements
completedHeaders (otherwise it makes little sense
to even decode the headers).

Basically this is a reimplementation of the functionality
of the old LLHTTPClientURLAdaptor class.

indra/llmessage/aihttpheaders.h

@@ -54,6 +54,9 @@ class AIHTTPHeaders {
 	// Construct a container with a single header.
 	AIHTTPHeaders(std::string const& key, std::string const& value);
 
+	// Clear all headers.
+	void clear(void) { if (mContainer) mContainer->mKeyValuePairs.clear(); }
+
 	// Add a header. Returns true if the header already existed.
 	bool addHeader(std::string const& key, std::string const& value, op_type op = new_header);
 
@@ -63,7 +66,7 @@ class AIHTTPHeaders {
 	// Return true if the header already exists.
 	bool hasHeader(std::string const& key) const;
 
-	// Return true if key exists and full value_out with the value. Return false otherwise.
+	// Return true if key exists and fill value_out with the value. Return false otherwise.
 	bool getValue(std::string const& key, std::string& value_out) const;
 
 	// Append the headers to slist.