Bump CMake min version for IBIze and clean up build files

Bump the CMake minimum version for IBIze to make it generate Makefiles
without errors or warnings about unsupported or deprecated CMake
versions.

Delete the top-level CMake file, as IBIze is the only CMake project in
OpenJK-Tools. Add the project definition in the ibize subdirectory and
adjust the README accordingly.

Author: mschwan

CMakeLists.txt

@@ -6,34 +6,36 @@ the GNU GPLv2 license.
 
 ## Building the code
 
-The OpenJK tools use CMake to generate the project files or makefiles for the
-source code. The project files or makefiles can then be used to compile the
-source code.
+IBIze is being built using CMake and generated Makefiles. This works on all
+platforms, including Windows, Linux and MacOS.
+
+ModView and Assimilate are Visual Studio projects and as such only work on
+Windows.
 
 
 ### Windows
 
 Generate the project files either by following the Linux and macOS instructions
-or by using the CMake GUI. For the CMake GUI, the source directory should be
-the root of the repository. The build directory is a directory of your choice
-where the project files will be generated.
+or by using the CMake GUI. For the CMake GUI, the source directory should be the
+`ibize` directory in this repository. The build directory is a directory of your
+choice where the project files will be generated, e.g. `ibize/build/`.
 
 Load the generated project file (likely to be a Visual Studio project), and
 then build in the IDE.
 
 
 ### Linux and macOS
 
-Generate the makefiles by running:
+Generate the makefiles (for IBIze only) by running:
 ```bash
+cd ibize
 mkdir build
 cd build
 cmake ..
 ```
 
-Compile the code:
+Compile the code, while being in `ibize/build/`:
 ```bash
-cd build
 make
 ```
 

README.md

@@ -1,3 +1,8 @@
+cmake_minimum_required(VERSION 3.1...3.31)
+project(IBIze)
+
+set(CMAKE_CXX_STANDARD 11)
+
 add_executable(ibize
 	blockstream.cpp
 	ibize.cpp