test: Add a check for too long or badly reflowed docstrings

This ensures that docstring comments are wrapped to 80 chars. ffrank
seemed to be making this mistake far too often, and it's a silly thing
to look for manually. As it turns out, I've made it too, as have many
others. Now we have a test that checks for most cases. There are still a
few stray cases that aren't checked automatically, but this can be
improved upon if someone is motivated to do so.

Before anyone complains about the 80 character limit: this only checks
docstring comments, not source code length or inline source code
comments. There's no excuse for having docstrings that are badly
reflowed or over 80 chars, particularly if you have an automated test.

engine/resources/exec.go

@@ -553,7 +553,8 @@ func (obj *ExecResAutoEdges) Next() []engine.ResUID {
 	return obj.edges
 }
 
-// Test gets results of the earlier Next() call, & returns if we should continue!
+// Test gets results of the earlier Next() call, & returns if we should
+// continue!
 func (obj *ExecResAutoEdges) Test(input []bool) bool {
 	return false // never keep going
 	// TODO: we could return false if we find as many edges as the number of different path's in cmdFiles()
@@ -578,8 +579,8 @@ func (obj *ExecRes) AutoEdges() (engine.AutoEdge, error) {
 	}, nil
 }
 
-// UIDs includes all params to make a unique identification of this object.
-// Most resources only return one, although some resources can return multiple.
+// UIDs includes all params to make a unique identification of this object. Most
+// resources only return one, although some resources can return multiple.
 func (obj *ExecRes) UIDs() []engine.ResUID {
 	x := &ExecUID{
 		BaseUID: engine.BaseUID{Name: obj.Name(), Kind: obj.Kind()},
@@ -609,8 +610,8 @@ func (obj *ExecRes) Sends() interface{} {
 	}
 }
 
-// UnmarshalYAML is the custom unmarshal handler for this struct.
-// It is primarily useful for setting the defaults.
+// UnmarshalYAML is the custom unmarshal handler for this struct. It is
+// primarily useful for setting the defaults.
 func (obj *ExecRes) UnmarshalYAML(unmarshal func(interface{}) error) error {
 	type rawRes ExecRes // indirection to avoid infinite recursion
 
@@ -690,9 +691,9 @@ type cmdOutput struct {
 }
 
 // cmdOutputRunner wraps the Cmd in with a StdoutPipe scanner and reads for
-// errors. It runs Start and Wait, and errors runtime things in the channel.
-// If it can't start up the command, it will fail early. Once it's running, it
-// will return the channel which can be used for the duration of the process.
+// errors. It runs Start and Wait, and errors runtime things in the channel. If
+// it can't start up the command, it will fail early. Once it's running, it will
+// return the channel which can be used for the duration of the process.
 // Cancelling the context merely unblocks the sending on the output channel, it
 // does not Kill the cmd process. For that you must do it yourself elsewhere.
 func (obj *ExecRes) cmdOutputRunner(ctx context.Context, cmd *exec.Cmd) (chan *cmdOutput, error) {