code organization: rename files

Hopefully more clear.

diff --git a/fsnotify_linux.go b/inotify_linux.go
similarity index 100%
rename from fsnotify_linux.go
rename to inotify_linux.go

diff --git a/fsnotify_test.go b/integration_test.go
similarity index 100%
rename from fsnotify_test.go
rename to integration_test.go

diff --git a/fsnotify_bsd.go b/kqueue.go
similarity index 100%
rename from fsnotify_bsd.go
rename to kqueue.go

diff --git a/fsnotify_open_bsd.go b/open_mode_bsd.go
similarity index 100%
rename from fsnotify_open_bsd.go
rename to open_mode_bsd.go

diff --git a/fsnotify_open_darwin.go b/open_mode_darwin.go
similarity index 100%
rename from fsnotify_open_darwin.go
rename to open_mode_darwin.go

diff --git a/fsnotify_windows.go b/windows.go
similarity index 100%
rename from fsnotify_windows.go
rename to windows.go