CMake: Add ability to just print version string

CHANGES

@@ -50,6 +50,7 @@ Misc:
  - Core: Add generic checksum function
  - Feature: Support ImageMagick 7
  - All: Move time.h include to common.h
+ - CMake: Add ability to just print version string
 
 0.5.2: (2016-12-31)
 Bugfixes:

version.cmake

@@ -43,7 +43,9 @@ if(NOT GIT_BRANCH)
 	set(GIT_BRANCH "(unknown)")
 endif()
 
-if(NOT VERSION_STRING_CACHE OR NOT VERSION_STRING STREQUAL VERSION_STRING_CACHE)
+if(DEFINED PRINT_STRING)
+	message("${${PRINT_STRING}}")
+elseif(NOT VERSION_STRING_CACHE OR NOT VERSION_STRING STREQUAL VERSION_STRING_CACHE)
 	set(VERSION_STRING_CACHE ${VERSION_STRING} CACHE STRING "" FORCE)
 
 	if(CONFIG_FILE AND OUT_FILE)