Allow VS to Generate the Project (#2)

* Allow VS to Generate the Project

This PR allows scikit-build's CMake Generator to create a Visual Studio Solution (when opening the folder within Visual Studio).

This allows both Visual Studio and VSCode to see nanobind-related Intellisense when working with the example.  However, this probably won't let users bypass `pip install .` when building the project...

.gitignore

@@ -2,3 +2,8 @@ nanobind_test.egg-info
 _skbuild
 /dist
 __pycache__
+build
+*.pyd
+*.egg-info
+.vscode
+.vs

CMakeLists.txt

@@ -2,7 +2,7 @@ project(nanobind_example)
 cmake_minimum_required(VERSION 3.17...3.22)
 
 if (NOT SKBUILD)
-  message(FATAL_ERROR "This CMake file should be executed via scikit-build. "
+  message(WARNING "This CMake file should be executed via scikit-build. "
                       "Please run\n$ pip install .")
 endif()
 
@@ -16,6 +16,10 @@ if (SKBUILD)
   set(Python_EXECUTABLE "${PYTHON_EXECUTABLE}")
   set(Python_INCLUDE_DIR "${PYTHON_INCLUDE_DIR}")
   set(Python_LIBRARIES "${PYTHON_LIBRARY}")
+elseif (MSVC)
+  # MSVC needs a little extra help finding the Python library
+  find_package(PythonInterp)
+  find_package(Python)
 endif()
 find_package(Python COMPONENTS Interpreter Development.Module REQUIRED)