build STIR into a different directory and add it to the gitignore

.gitignore

@@ -4,6 +4,7 @@ venv/
 /data/
 /trainings/
 *.log
+libs/STIR_build
 
 jupyterhub*
 .ipynb_checkpoints/

libs/install.sh

@@ -5,6 +5,7 @@ GLOBAL_LIBS="libncurses-dev  libboost-dev  nlohmann-json3-dev swig libinsighttoo
 
 DIR_PARALLELPROJ="parallelproj"
 DIR_STIR="STIR"
+DIR_BUILD_STIR="STIR_build"
 
 if [ -z ${VIRTUAL_ENV} ]; then
     echo "ERROR:"
@@ -37,10 +38,12 @@ cd ../../
 
 ##################### STIR ###########################################
 echo "Install ${DIR_STIR} ..."
-mkdir -p ${DIR_STIR}/build && \
-cd ${DIR_STIR}/build && \
-cmake .. -DPYTHON_DEST=${PYTHON_DEST} -DBUILD_SWIG_PYTHON=ON -DSTIR_OPENMP=ON -DCMAKE_INSTALL_PREFIX=${VIRTUAL_ENV} && \
+# Note: we install STIR not in a build directory under the STIR clone because it does not specify such
+#       a directory in its gitignore, which means that `git status` will always show changes 
+mkdir -p ${DIR_BUILD_STIR} && \
+cd ${DIR_BUILD_STIR} && \
+cmake ../${DIR_STIR} -DPYTHON_DEST=${PYTHON_DEST} -DBUILD_SWIG_PYTHON=ON -DSTIR_OPENMP=ON -DCMAKE_INSTALL_PREFIX=${VIRTUAL_ENV} && \
 nice make -j ${MAKE_THREADS} && \
 make install && \
-cd ../../
+cd -