inotify: Retry read on EINTR

inotify: Retry read on EINTR #61 (thanks @PieterD)

another backport

• kqueue: cleanup internal watch before sending remove event #51

focus on kqueue

kqueue

• rework internals #43
• add low-level functions
• only need to store flags on directories
• less mutexes #13
• done can be an unbuffered channel
• remove calls to os.NewSyscallError
• fix regression in rework causing subdirectories to be watched #48
• cleanup internal watch before sending remove event #51

other

• More efficient string concatenation for Event.String() #52 (thanks @mdlayher)

DragonFly BSD

• kqueue: add dragonfly to the build tags.
• Rename source code files, rearrange code so exported APIs are at the top.
• Add done channel to example code. (thanks @chenyukang)

Fix: Windows rename consistiency

Windows MOVED_TO now translates to Create like on BSD and Linux.

Fix missing create events on macOS

• Missing create events on macOS. #14 (thanks @zhsso)
• Make ./path and path equivalent. (thanks @zhsso)

Backport

• Fix missing create events on macOS. #14 (thanks @zhsso)

A New API

• Improve documentation for exported identifiers. #30
• Minor updates based on feedback from golint.

v1 contains a number of API changes and improvements over v0.9.0. See the CHANGELOG for the full details.