Fix CoW in HTTPResponseAggregator (swift-server#345) Motivation: HTTPResponseAggregator attempts to build a single, complete response object. This necessarily means it loads the entire response payload into memory. It wants to provide this payload as a single contiguous buffer of data, and it does so by aggregating the data into a single contiguous buffer as it goes. Because ByteBuffer does exponential reallocation, the cost of doing this should be amortised constant-time, even though we do have to copy some data sometimes. However, if this operation triggers a copy-on-write then the operation will become quadratic. For large buffers this will rapidly come to dominate the runtime. Unfortunately in at least Swift 5.3 Swift cannot safely see that during the body stanza the state variable is dead. Swift is not necessarily wrong about this: there's a cross-module call to ByteBuffer.writeBuffer in place and Swift cannot easily prove that that call will not lead to a re-entrant access of the `HTTPResponseAggregator` object. For this reason, during the call to `didReceiveBodyPart` there will be two copies of the body buffer alive, and so the write will CoW. This quadratic behaviour is a nasty performance trap that can become highly apparent even at quite small body sizes. Modifications: While Swift can't prove that the `self.state` variable is dead, we can! To that end, we temporarily set it to a different value that does not store the buffer in question. This will force Swift to drop the ref on the buffer, making it uniquely owned and avoiding the CoW. Sadly, it's extremely difficult to test for "does not CoW", so this patch does not currently come with any tests. I have experimentally verified the behaviour. Result: No copy-on-write in the HTTPResponseAggregator during body aggregation.

Update Readme to account for Package.swift format (swift-server#339) Adding the product dependency to the target by name only produces an error in Xcode 12.4. Instead, the product dependency should be given as a `.product`. Updated the README with the new format, so that new user's won't stumble over this.

Fix Timeout snippet in README.md (swift-server#323) 

Fixes default timeout documentation comment (swift-server#317) Motivation: Right now documentation states that timrout defaults to no timeout, this is no actually true, if timeout is not set NIO bootstrap defaults to 10 seconds connect timeout. Modifications: Updates documentation comment. Result: Closesswift-server#118

Fix state reverting (swift-server#298) * fail if we get part when state is endOrError * Prevent TaskHandler state change after `.endOrError` Motivation: Right now if task handler encounters an error, it changes state to `.endOrError`. We gate on that state to make sure that we do not process errors in the pipeline twice. Unfortunately, that state can be reset when we upload body or receive response parts. Modifications: Adds state validation before state is updated to a new value Adds a test Result: Fixesswift-server#297

rename connection pool configuration (swift-server#288) 

fix location header lookup 

require secure NIO version (swift-server#162) 

fix NIO deprecations & update to secure versions (swift-server#141) 

add support for redirect limits (swift-server#113)