Remove ShowPlan

It is out of sync with reality, has some disabled tests, and the cost
of getting it up-to-date is too high to be worth it.

commands/check.go

@@ -19,24 +19,5 @@ import (
 
 var checkCmd = &cobra.Command{
 	Use:   "check",
-	Short: "Check content in the source directory",
-	Long: `Hugo will perform some basic analysis on the content provided
-and will give feedback.`,
-}
-
-func init() {
-	initHugoBuilderFlags(checkCmd)
-	checkCmd.RunE = check
-}
-
-func check(cmd *cobra.Command, args []string) error {
-	if err := InitializeConfig(checkCmd); err != nil {
-		return err
-	}
-
-	if err := initSites(); err != nil {
-		return err
-	}
-
-	return Hugo.Analyze()
+	Short: "Contains some verification checks",
 }