SFTPStream open Unknown flags

[fredericosilva]

Hello,

While proxying SFTPStream events I've came across with unmapped flags

'11':  OPEN_MODE.CREAT | OPEN_MODE.WRITE | OPEN_MODE.READ
'19':  OPEN_MODE.TRUNC | OPEN_MODE.WRITE | OPEN_MODE.READ
'43':  OPEN_MODE.EXCL | OPEN_MODE.CREAT | OPEN_MODE.WRITE | OPEN_MODE.READ

I'm thinking about adding those flags to the stringFlagMap or a more generic approach by adding integer flags_ support on SFTPStream.open

var flags = Number.isInteger(flags_) ? flags_ : stringToFlags(flags_);

Any thoughts?

[DaneEveritt]

Add the one below to this list as well, Cyberduck sends it when doing a file overwrite (which might just be Cyberduck being annoying). That PR would be excellent for avoiding having to remap the flag before I pass it into my handler logic.

'18' : OPEN_MODE.TRUNC | OPEN_MODE.CREAT

[DaneEveritt]

Cyberduck is also sending '24' as a flag when creating a new file in a directory.