Added cmake file to compute version information

- Reads BERGAMOT_VERSION file for generating various strings
   for versioning

cmake/GetVersionFromFile.cmake

@@ -0,0 +1,60 @@
+##
+# This CMake modules sets the project version from a version file.
+#
+# The module sets the following variables:
+#
+# * PROJECT_VERSION_STRING
+# * PROJECT_VERSION_STRING_FULL
+# * PROJECT_VERSION_MAJOR
+# * PROJECT_VERSION_MINOR
+# * PROJECT_VERSION_PATCH
+# * PROJECT_VERSION_TWEAK
+# * PROJECT_VERSION_GIT_SHA
+#
+# This module is public domain, use it as it fits you best.
+##
+
+# Get full string version from file
+if(PROJECT_VERSION_FILE)
+  file(STRINGS ${PROJECT_VERSION_FILE} PROJECT_VERSION_STRING)
+else()
+  file(STRINGS ${CMAKE_CURRENT_SOURCE_DIR}/BERGAMOT_VERSION PROJECT_VERSION_STRING)
+endif()
+
+# Get current commit SHA from git
+execute_process(COMMAND ${GIT_EXECUTABLE} rev-parse --short HEAD
+  WORKING_DIRECTORY ${CMAKE_SOURCE_DIR}
+  OUTPUT_VARIABLE PROJECT_VERSION_GIT_SHA
+  OUTPUT_STRIP_TRAILING_WHITESPACE)
+
+# Get partial versions into a list
+string(REGEX MATCHALL "-.*$|[0-9]+" PROJECT_PARTIAL_VERSION_LIST
+  ${PROJECT_VERSION_STRING})
+
+# Set the version numbers
+list(GET PROJECT_PARTIAL_VERSION_LIST 0 PROJECT_VERSION_MAJOR)
+list(GET PROJECT_PARTIAL_VERSION_LIST 1 PROJECT_VERSION_MINOR)
+list(GET PROJECT_PARTIAL_VERSION_LIST 2 PROJECT_VERSION_PATCH)
+
+# The tweak part is optional, so check if the list contains it
+list(LENGTH PROJECT_PARTIAL_VERSION_LIST PROJECT_PARTIAL_VERSION_LIST_LEN)
+if(PROJECT_PARTIAL_VERSION_LIST_LEN GREATER 3)
+  list(GET PROJECT_PARTIAL_VERSION_LIST 3 PROJECT_VERSION_TWEAK)
+  string(SUBSTRING ${PROJECT_VERSION_TWEAK} 1 -1 PROJECT_VERSION_TWEAK)
+endif()
+
+# Unset the list
+unset(PROJECT_PARTIAL_VERSION_LIST)
+
+# Set full project version string
+set(PROJECT_VERSION_STRING_FULL
+  ${PROJECT_VERSION_STRING}+${PROJECT_VERSION_GIT_SHA})
+
+# Print all variables for debugging
+#message(STATUS ${PROJECT_VERSION_STRING_FULL})
+#message(STATUS ${PROJECT_VERSION_STRING})
+#message(STATUS ${PROJECT_VERSION_MAJOR})
+#message(STATUS ${PROJECT_VERSION_MINOR})
+#message(STATUS ${PROJECT_VERSION_PATCH})
+#message(STATUS ${PROJECT_VERSION_TWEAK})
+#message(STATUS ${PROJECT_VERSION_GIT_SHA})