deleted some duplicated preprocessor handling

also:
- updated test and dox submodules
- updated README

.github/ISSUE_TEMPLATE/bug_report.md

@@ -11,7 +11,7 @@ Replace the _italic_ text below with the relevant information to help me underst
 
 ## Environment
 **Compiler:**  
-_The compiler & version, e.g. "Clang 9"_  
+_The compiler & version, e.g. "Clang 9, Visual Studio 2019 16.5"_  
 
 **C++ standard mode (e.g. 17, 20, 'latest'):**  
 _The C++ standard level you were targeting, e.g. C++17_  

README.md

@@ -166,16 +166,17 @@ If you wish to submit a pull request, please see [CONTRIBUTING] for all the deta
 UTF-8 decoding is performed using a state machine based on Bjoern Hoehrmann's '[Flexible and Economical UTF-8 Decoder]'.
 
 ### With thanks to:
-- **@bjadamson** - Reported some bugs and helped design a new feature
-- **@bobfang1992** - Reported a bug and created a [wrapper in python](https://github.com/bobfang1992/pytomlpp)
-- **@GiulioRomualdi** - Added cmake+meson support
-- **@mosra** - Created the awesome [m.css] used to generate the API docs
-- **@ned14** - Reported a bunch of bugs and helped design some new features
-- **@prince-chrismc** - Added `toml++` to ConanCenter, and fixed some typos
-- **@rbrugo** - helped design a new feature
-- **@shdnx** - Fixed a bug on GCC 8.2.0 and some meson config issues
-- **@traversaro** - Added vcpkg support and reported a bunch of bugs
-- **@ximion** - Added support for installation with meson
+- **[@bjadamson](github.com/bjadamson)** - Reported some bugs and helped design a new feature
+- **[@bobfang1992](github.com/bobfang1992)** - Reported a bug and created a [wrapper in python](https://github.com/bobfang1992/pytomlpp)
+- **[@GiulioRomualdi](github.com/GiulioRomualdi)** - Added cmake+meson support
+- **[@mosra](github.com/mosra)** - Created the awesome [m.css] used to generate the API docs
+- **[@ned14](github.com/ned14)** - Reported a bunch of bugs and helped design some new features
+- **[@okureta](github.com/okureta)** - Reported a bug
+- **[@prince-chrismc](github.com/prince-chrismc)** - Added `toml++` to ConanCenter, and fixed some typos
+- **[@rbrugo](github.com/rbrugo)** - Helped design a new feature
+- **[@shdnx](github.com/shdnx)** - Fixed a bug on GCC 8.2.0 and some meson config issues
+- **[@traversaro](github.com/traversaro)** - Added vcpkg support and reported a bunch of bugs
+- **[@ximion](github.com/ximion)** - Added support for installation with meson
 
 <br>
 

extern/Catch2

@@ -1 +1 @@
-Subproject commit b1dcdc5032f09cab0a5834476d85e999bb608ce6
+Subproject commit 53999216221a8b38bf619ddee6a48107f5bfc7c9

extern/mcss

@@ -1 +1 @@
-Subproject commit e6166bf3aee773fc38211eb72249e4e1d633f51e
+Subproject commit e6eff549fb5edeabacf01369d6b845a2a59c2ebe

include/toml++/toml_common.h

@@ -25,14 +25,6 @@ TOML_DISABLE_ALL_WARNINGS
 #ifndef TOML_OPTIONAL_TYPE
 	#include <optional>
 #endif
-#ifndef TOML_ASSERT
-	#ifdef NDEBUG
-		#define TOML_ASSERT(expr)	(void)0
-	#else
-		#include <cassert>
-		#define TOML_ASSERT(expr)	assert(expr)
-	#endif
-#endif
 
 TOML_POP_WARNINGS
 

include/toml++/toml_parser.hpp

@@ -195,7 +195,7 @@ namespace toml::impl
 		#define TOML_RETURNS_BY_THROWING
 	#endif
 
-	#ifdef NDEBUG
+	#if defined(NDEBUG) || !defined(_DEBUG)
 		#define assert_or_assume(cond)			TOML_ASSUME(cond)
 	#else
 		#define assert_or_assume(cond)			TOML_ASSERT(cond)

include/toml++/toml_preprocessor.h

@@ -368,7 +368,7 @@
 TOML_PUSH_WARNINGS
 TOML_DISABLE_ALL_WARNINGS
 #ifndef TOML_ASSERT
-	#ifdef NDEBUG
+	#if defined(NDEBUG) || !defined(_DEBUG)
 		#define TOML_ASSERT(expr)	(void)0
 	#else
 		#include <cassert>

toml.hpp

@@ -385,7 +385,7 @@
 TOML_PUSH_WARNINGS
 TOML_DISABLE_ALL_WARNINGS
 #ifndef TOML_ASSERT
-	#ifdef NDEBUG
+	#if defined(NDEBUG) || !defined(_DEBUG)
 		#define TOML_ASSERT(expr)	(void)0
 	#else
 		#include <cassert>
@@ -424,14 +424,6 @@ TOML_DISABLE_ALL_WARNINGS
 #ifndef TOML_OPTIONAL_TYPE
 	#include <optional>
 #endif
-#ifndef TOML_ASSERT
-	#ifdef NDEBUG
-		#define TOML_ASSERT(expr)	(void)0
-	#else
-		#include <cassert>
-		#define TOML_ASSERT(expr)	assert(expr)
-	#endif
-#endif
 
 TOML_POP_WARNINGS
 
@@ -6873,7 +6865,7 @@ namespace toml::impl
 		#define TOML_RETURNS_BY_THROWING
 	#endif
 
-	#ifdef NDEBUG
+	#if defined(NDEBUG) || !defined(_DEBUG)
 		#define assert_or_assume(cond)			TOML_ASSUME(cond)
 	#else
 		#define assert_or_assume(cond)			TOML_ASSERT(cond)