Prepare release v0.4.0 - Githubissues

Major release is there: version 0.4.0 ready to ship!!!

Since version 0.3.0, these are the main changes (from release notes):

overhaul all doc comments, add exceptions, improve IDE quick-info experience, #136, #220, #234 (in coop with @bartelink)
new surface area functions, fixes #208:
- TaskSeq.take, skip, #209
- TaskSeq.truncate, drop, #209
- TaskSeq.where, whereAsync, #217
- TaskSeq.skipWhile, skipWhileInclusive, skipWhileAsync, skipWhileInclusiveAsync, #219
- TaskSeq.max, min, maxBy, minBy, maxByAsync, minByAsync, #221
- TaskSeq.insertAt, insertManyAt, removeAt, removeManyAt, updateAt, #236
- TaskSeq.forall, forallAsync, #240
- TaskSeq.concat (overloads: seq, array, resizearray, list), #237
Performance: less thread hops with 'StartImmediateAsTask' instead of 'StartAsTask', fixes #135
Performance: several inline and allocation improvements
BINARY INCOMPATIBILITY: TaskSeq module replaced by static members on TaskSeq<_>, fixes #184
- applies to all functions in TaskSeq.xxxx space
- any existing code can simply be recompiled
- replacing the library without recompiling may lead to errors
DEPRECATIONS (warning FS0044, old names can still be used):
- type taskSeq<_> is renamed to TaskSeq<_>, fixes #193
- function ValueTask.ofIValueTaskSource renamed to ValueTask.ofSource, fixes #193
- function ValueTask.FromResult is renamed to ValueTask.fromResult, fixes #193

fixes not calling Dispose for 'use!', 'use', or finally blocks #157 (by @bartelink)
BREAKING CHANGE: null args now raise ArgumentNullException instead of NullReferenceException, #127
adds let! and do! support for F#'s Async<'T>, #79, #114
adds TaskSeq.takeWhile, takeWhileAsync, takeWhileInclusive, takeWhileInclusiveAsync, #126 (by @bartelink)
adds AsyncSeq vs TaskSeq comparison chart, #131
removes release-notes.txt from file dependencies, but keep in the package, #138