updating structure of the CMake build system

build_spectral.sh

@@ -0,0 +1,19 @@
+#!/bin/bash
+
+cat  README
+echo "Building spectral solver with ${FC}"
+
+# prepare building directory
+if [ ! -d build_spectral ] ; then
+    mkdir build_spectral
+fi
+cd build_spectral
+
+# start building
+cmake -D PETSC_DIR=${PETSC_DIR} \
+      -D HDF5=${HDF5} \
+      ..
+
+# instruction for compiling
+echo "Please go into build_spectral directory and use make"
+echo "to build DAMASK_spectal.exe"