update bullet so it actually works

Moved the addSourceDirectory for physics/Bullet into the Engine/Source/CMakeLists.txt file that way it can actually appear where we expect it to in the solution explorer.

Engine/lib/bullet/.gitignore

@@ -0,0 +1,42 @@
+/bin
+/build3/gmake
+/build3/vs2010
+/build_cmake/
+
+*.pyc
+
+# Python
+__pycache__/
+*.py[cod]
+
+# Pip
+pip-selfcheck.json
+*.whl
+*.egg
+*.egg-info
+
+# Setuptools
+/build
+/dist
+*.eggs
+
+# CMake
+CMakeFiles/
+CMakeCache.txt
+cmake_install.cmake
+CTestTestFile.cmake
+
+# Visual Studio build files
+*.vcxproj
+*.vcxproj.filters
+*.sln
+
+# Apple Finder metadata
+*.DS_Store
+
+# vim temp files
+*.swp
+
+.vscode/
+.idea/
+cmake-build-debug/