Add Write Concern support

[Fonger]

Add write concern helpers

w writeConcern j wtimeout wTimeout

mquery().writeConcern(1)
mquery().writeConcern({ w: 1, j: true, wtimeout: 2000 })
mquery().w(1).j(true).wtimeout(2000)
mquery().writeConcern('majority')

// same as majority. keep the same behavior with read concern/read preference
mquery().writeConcern('m')

// if the tag set happens to be 'm', use .writeConcern({ w: 'm' }) instead.
mquery().writeConcern('tagSetName')
mquery().w(1) // w is alias of writeConcern

The special case is that write concern accepts object and it will parse the object to the underlying options correctly. Also, .w('m') is alias of .w('majority'). Mongoose does not has this implementation.

Add r as alias of readConcern

as w is for writeConcern

Add setReadPreference as alias of read

mquery use .read() to set read preference. However, node-mongodb-native has different meaning
IMO, this method is for internal use. I think it's okay to overwrite this behavior.

node-mongodb-native uses setReadPreference to specify read preference.

Add hint test

Add findOneAndDelete alias of findOneAndRemove

[vkarpov15]

LGTM in general, just one quick comment

[vkarpov15]

I'm not sure I like supporting 'm' as a shortcut for 'majority'. Is there some precedent for this?

[Fonger]

mquery ReadPreference .read() support abbrevation.
https://github.com/aheckmann/mquery/blob/45c4bd104613da47828df13d4aec12c324525c53/lib/mquery.js#L1583-L1596

In my previous request, I make readConcern() also support abbrevation. m = majority
https://github.com/aheckmann/mquery/blob/45c4bd104613da47828df13d4aec12c324525c53/lib/mquery.js#L1640-L1653

So I make writeConcern() to accept 'm' as shortcut as well.
I doubt if it is ok to support m in write concern too. If the tag name happens to be m, it will be replaced with majority.

For consistency, maybe we should make a breaking change to not support m as alias of majority in read concern either? Only read preference accept alias names.

In read concern, l=local, lz = linearizable. I think lz is not good abbreviation but I can't find good alternative.

[vkarpov15]

Yeah you're right, this is more consistent with the readConcern and read APIs, let's merge this