Bump version post 0.1 for development. (#623)

cf. CMake issue 16716: https://gitlab.kitware.com/cmake/cmake/issues/16716

* Bump version post 0.1 for development.
* Read version string from file VERSION.
* Strip suffix to make a numerical, CMake-compatible PROJECT_VERSION.

CMakeLists.txt

 # 3.8 requirement for CUDA language support.
 cmake_minimum_required(VERSION 3.8)
 
-project(arbor VERSION 0.1)
+file(READ VERSION FULL_VERSION_STRING)
+string(STRIP "${FULL_VERSION_STRING}" FULL_VERSION_STRING)
+string(REGEX MATCH "^[0-9]+(\\.[0-9]+)?(\\.[0-9]+)?(\\.[0-9]+)?" numeric_version "${FULL_VERSION_STRING}")
+
+project(arbor VERSION ${numeric_version})
 enable_language(CXX)
 
+
 #----------------------------------------------------------
 # Configure-time build options for Arbor:
 #----------------------------------------------------------

VERSION

+0.1.1-dev

include/CMakeLists.txt

@@ -46,7 +46,7 @@ endif()
 add_custom_command(
     OUTPUT version.hpp-test
     DEPENDS _always_rebuild
-    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/git-source-id ${PROJECT_VERSION} ${arb_features} > version.hpp-test
+    COMMAND ${CMAKE_CURRENT_SOURCE_DIR}/git-source-id ${FULL_VERSION_STRING} ${arb_features} > version.hpp-test
 )
 
 set(version_hpp_path arbor/version.hpp)