cancelRequests should be on by default

[rbu]

cancelRequests is a very useful feature setting and should be enabled by default.

We had not noticed autoComplete does not automatically cancel requests (or discard them for other reasons, e.g. since it realized better results were already received) because we are developing on a single-threaded server. Only when we deployed in a multi-threaded environment with real data (where queries for shorter terms return more results, thus take longer to transfer!), we realized this feature was actually off. It is not even documented in the README.