Added script for installing CLASS

install_class.sh

+#!/usr/bin/env sh
+
+set -e
+# installer for CLASS when using a conda environment
+CLASS_DIR="class_public"
+CLASS_REMOTE_URL="https://github.com/JCGoran/class_public"
+CLASS_BRANCH="feature/conda"
+
+install_class(){
+    if [ -z "${CONDA_PREFIX}" ]
+    then
+        printf 'You need to activate a conda environment using `conda activate [ENVIRONMENT]` before running this script\n'
+        return 1
+    fi
+
+    if [ ! -d "${CLASS_DIR}" ]
+    then
+        printf 'Attempting to install CLASS in the current environment (%s)...\n' "${CONDA_DEFAULT_ENV}"
+        printf 'Cloning to directory %s...\n' "${CLASS_DIR}"
+        git clone --branch "${CLASS_BRANCH}" "${CLASS_REMOTE_URL}" "${CLASS_DIR}"
+    fi
+
+    make -C "${CLASS_DIR}" libclass.a && cp -a "${CLASS_DIR}/libclass.a" "${CONDA_PREFIX}/lib/" && cp -a "${CLASS_DIR}/include/"*.h "${CONDA_PREFIX}/include/"
+    printf 'CLASS successfully installed\n'
+}
+
+install_class
+set +e