Align docs and dependencies

CMakeLists.txt

@@ -1,4 +1,4 @@
-cmake_minimum_required(VERSION 3.16)
+cmake_minimum_required(VERSION 3.18)
 
 # Not ideal to use this global variable, but necessary to make sure
 # that tooling and projects use the same version
@@ -24,7 +24,7 @@ set(OPT_WARNINGS_AS_ERRORS_DEVELOPER_DEFAULT TRUE)
 # https://github.com/cpp-best-practices/project_options
 include(FetchContent)
 FetchContent_Declare(_project_options
-                     URL https://github.com/cpp-best-practices/project_options/archive/refs/tags/v0.17.0.zip)
+                     URL https://github.com/cpp-best-practices/project_options/archive/refs/tags/v0.20.0.zip)
 FetchContent_MakeAvailable(_project_options)
 include(${_project_options_SOURCE_DIR}/Index.cmake)
 
@@ -92,6 +92,7 @@ dynamic_project_options(
   PCH_HEADERS
   <vector>
   <string> # This is a list of headers to pre-compile, here are some common ones
+  ENABLE_CONAN       # Use Conan for package management
   # CONAN_OPTIONS    # Extra options to pass to conan
   # MSVC_WARNINGS    # Override the defaults for the MSVC warnings
   # CLANG_WARNINGS   # Override the defaults for the CLANG warnings

README_dependencies.md

@@ -29,18 +29,23 @@ RefreshEnv.cmd # reload the environment
 ```
 
 ### Necessary Dependencies
-1. A C++ compiler that supports C++17.
+1. A C++ compiler that supports C++20.
 See [cppreference.com](https://en.cppreference.com/w/cpp/compiler_support)
 to see which features are supported by each compiler.
 The following compilers should work:
 
-  * [gcc 7+](https://gcc.gnu.org/)
+  * [gcc 11+](https://gcc.gnu.org/)
 	<details>
 	<summary>Install command</summary>
 
-	- Debian/Ubuntu:
+	- Ubuntu 21.04+:
+
+			sudo apt install gcc-11
+
+	- Ubuntu 18.04-20.04:
 
-			sudo apt install build-essential
+			sudo add-apt-repository -y ppa:ubuntu-toolchain-r/test && sudo apt-get update -qq
+			sudo apt install gcc-11
 
 	- Windows:
 
@@ -51,7 +56,7 @@ The following compilers should work:
 			brew install gcc
 	</details>
 
-  * [clang 6+](https://clang.llvm.org/)
+  * [clang 13+](https://clang.llvm.org/)
 	<details>
 	<summary>Install command</summary>
 
@@ -107,10 +112,15 @@ The following compilers should work:
 	<details>
 	<summary>Install Command</summary>
 
-	- Via pip - https://docs.conan.io/en/latest/installation.html#install-with-pip-recommended
+	- Via pip (requires Python 3.5+) - https://docs.conan.io/en/latest/installation.html#install-with-pip-recommended
 
 			pip install --user conan
 
+	  Over time, you may need to upgrade Conan to maintain compatibility with the latest packages.
+	  You can do that with:
+
+			pip install --user --upgrade conan
+
 	- Windows:
 
 			choco install conan -y
@@ -121,13 +131,19 @@ The following compilers should work:
 
 	</details>
 
-3. [CMake 3.15+](https://cmake.org/)
+3. [CMake 3.18+](https://cmake.org/)
 	<details>
 	<summary>Install Command</summary>
 
-	- Debian/Ubuntu:
+    - All platforms (if you have Python installed):
+
+			pip install --user cmake
+
+    - Ubuntu 21.04 or later:
+
+            sudo apt-get install cmake cmake-curses-gui
 
-			sudo apt-get install cmake
+    - Ubuntu 16.04-20.04: Follow instructions at [Kitware](https://apt.kitware.com/)
 
 	- Windows:
 
@@ -139,7 +155,7 @@ The following compilers should work:
 
 	</details>
 
-### Optional Dependencies
+### Strongly Recommended (but optional) Dependencies
 #### C++ Tools
   * [Doxygen](http://doxygen.nl/)
 	<details>
@@ -226,7 +242,10 @@ If you run into difficulty using them, please refer to their documentation,
 linked here:
 
 - [NANA](http://nanapro.org/en-us/documentation/)
-- [SDL](http://wiki.libsdl.org/FrontPage)
+- [SDL](http://wiki.libsdl.org/FrontPage):
+  Please note that the Conan package for SDL can be challenging to build on some platforms.
+  If you need to use SDL, you may find it easier to install using the
+  [official instructions](http://wiki.libsdl.org/Installation) than to use the Conan package.
 - [IMGUI](https://github.com/ocornut/imgui/tree/master/docs):
   This framework depends on SFML, and if you are using Linux, you may need
   to install several of SFML's dependencies using your package manager. See