engine: Resources package rewrite

This giant patch makes some much needed improvements to the code base.

* The engine has been rewritten and lives within engine/graph/
* All of the common interfaces and code now live in engine/
* All of the resources are in one package called engine/resources/
* The Res API can use different "traits" from engine/traits/
* The Res API has been simplified to hide many of the old internals
* The Watch & Process loops were previously inverted, but is now fixed
* The likelihood of package cycles has been reduced drastically
* And much, much more...

Unfortunately, some code had to be temporarily removed. The remote code
had to be taken out, as did the prometheus code. We hope to have these
back in new forms as soon as possible.

gapi/gapi.go

@@ -22,8 +22,8 @@ import (
 	"encoding/gob"
 	"fmt"
 
+	"github.com/purpleidea/mgmt/engine"
 	"github.com/purpleidea/mgmt/pgraph"
-	"github.com/purpleidea/mgmt/resources"
 
 	"github.com/urfave/cli"
 )
@@ -46,7 +46,7 @@ func Register(name string, fn func() GAPI) {
 type Data struct {
 	Program       string // name of the originating program
 	Hostname      string // uuid for the host, required for GAPI
-	World         resources.World
+	World         engine.World
 	Noop          bool
 	NoConfigWatch bool
 	NoStreamWatch bool
@@ -70,7 +70,7 @@ type Next struct {
 
 // GAPI is a Graph API that represents incoming graphs and change streams.
 type GAPI interface {
-	Cli(c *cli.Context, fs resources.Fs) (*Deploy, error)
+	Cli(c *cli.Context, fs engine.Fs) (*Deploy, error)
 	CliFlags() []cli.Flag
 
 	Init(Data) error               // initializes the GAPI and passes in useful data