config: reintroduce ENTT_DISABLE_ASSERT (close #599)

docs/md/config.md

@@ -12,6 +12,7 @@
   * [ENTT_ID_TYPE](#entt_id_type)
   * [ENTT_PAGE_SIZE](#entt_page_size)
   * [ENTT_ASSERT](#entt_assert)
+    * [ENTT_DISABLE_ASSERT](#entt_disable_assert)
   * [ENTT_NO_ETO](#entt_no_eto)
   * [ENTT_STANDARD_CPP](#entt_standard_cpp)
 
@@ -71,10 +72,17 @@ all case, the chosen value **must** be a power of 2.
 For performance reasons, `EnTT` doesn't use exceptions or any other control
 structures. In fact, it offers many features that result in undefined behavior
 if not used correctly.<br/>
-To get around this, the library relies on a lot of `assert`s for the purpose of
-detecting errors in debug builds. However, these assertions may in turn affect
-performance to an extent.<br/>
-This option is meant to disable all controls.
+To get around this, the library relies on a lot of asserts for the purpose of
+detecting errors in debug builds. By default, it uses `assert` internally, but
+users are allowed to overwrite its behavior by setting this variable.
+
+### ENTT_DISABLE_ASSERT
+
+Assertions may in turn affect performance to an extent when enabled. Whether
+`ENTT_ASSERT` is redefined or not, all asserts can be disabled at once by means
+of this definition.<br/>
+Note that `ENTT_DISABLE_ASSERT` takes precedence over the redefinition of
+`ENTT_ASSERT` and is therefore meant to disable all controls no matter what.
 
 ## ENTT_NO_ETO
 

src/entt/config/config.h

@@ -26,7 +26,10 @@
 #endif
 
 
-#ifndef ENTT_ASSERT
+#ifdef ENTT_DISABLE_ASSERT
+#   undef ENTT_ASSERT
+#   define ENTT_ASSERT(...) (void(0))
+#elif !defined ENTT_ASSERT
 #   include <cassert>
 #   define ENTT_ASSERT(condition) assert(condition)
 #endif