change Bullet's feature enable logic

README.md

@@ -121,8 +121,6 @@ Bullet.unused_eager_loading_enable = false
 Bullet.counter_cache_enable        = false
 ```
 
-Note: When calling `Bullet.enable`, all other detectors are reset to their defaults (`true`) and need reconfiguring.
-
 ## Safe list
 
 Sometimes Bullet may notify you of query problems you don't care to fix, or

lib/bullet.rb

@@ -64,7 +64,11 @@ def raise=(should_raise)
     ].freeze
 
     def enable=(enable)
-      @enable = @n_plus_one_query_enable = @unused_eager_loading_enable = @counter_cache_enable = enable
+      @enable = enable
+
+      @n_plus_one_query_enable = true if @n_plus_one_query_enable.nil?
+      @unused_eager_loading_enable = true if @unused_eager_loading_enable.nil?
+      @counter_cache_enable = true if @counter_cache_enable.nil?
 
       if enable?
         reset_safelist
@@ -90,15 +94,27 @@ def app_root
     end
 
     def n_plus_one_query_enable?
-      enable? && !!@n_plus_one_query_enable
+      enable? && default_n_plus_one_query_enable?
     end
 
     def unused_eager_loading_enable?
-      enable? && !!@unused_eager_loading_enable
+      enable? && default_unused_eager_loading_enable?
     end
 
     def counter_cache_enable?
-      enable? && !!@counter_cache_enable
+      enable? && default_counter_cache_enable?
+    end
+
+    def default_n_plus_one_query_enable?
+      !!@n_plus_one_query_enable
+    end
+
+    def default_unused_eager_loading_enable?
+      !!@unused_eager_loading_enable
+    end
+
+    def default_counter_cache_enable?
+      !!@counter_cache_enable
     end
 
     def stacktrace_includes