Separate the library version from the project version

To make it easier to maintain things in the future in case of any
ABI or API breaks, split the library versioning to a new variable.

CMakeLists.txt

@@ -1,6 +1,7 @@
 cmake_minimum_required(VERSION 3.5)
 
-project(maliit-framework VERSION 2.3.0)
+project(maliit-framework VERSION 2.99.0)
+set(LIBRARY_VERSION 3.0.0)
 
 # Build options
 
@@ -203,8 +204,8 @@ target_link_libraries(maliit-plugins PRIVATE maliit-common maliit-connection ${P
 target_link_libraries(maliit-plugins PUBLIC Qt5::Core Qt5::Gui Qt5::Quick)
 target_include_directories(maliit-plugins PRIVATE ${PLUGINS_INCLUDE_DIRS})
 
-set_target_properties(maliit-plugins PROPERTIES SOVERSION ${PROJECT_VERSION_MAJOR}
-        VERSION ${PROJECT_VERSION}
+set_target_properties(maliit-plugins PROPERTIES
+        VERSION ${LIBRARY_VERSION}
         EXPORT_NAME Maliit::Plugins)
 
 if(enable-glib)
@@ -242,8 +243,8 @@ if(enable-glib)
     add_library(maliit-glib SHARED ${GLIB_SOURCES} ${GLIB_HEADER})
     target_include_directories(maliit-glib PUBLIC ${GIO_INCLUDE_DIRS})
     target_link_libraries(maliit-glib ${GIO_LIBRARIES})
-    set_target_properties(maliit-glib PROPERTIES SOVERSION ${PROJECT_VERSION_MAJOR}
-            VERSION ${PROJECT_VERSION}
+    set_target_properties(maliit-glib PROPERTIES
+            VERSION ${LIBRARY_VERSION}
             EXPORT_NAME Maliit::GLib)
 endif()