Remove incomplete installation support

Installing applications with runtime assets like fonts and shared
libraries is not trivial. This single install command gives users
the impression that they can install their programs but falls short
of what many users would need so for now we're better off removing
it until we can provide a more robust one-size-fits-all solution
for installation.

CMakeLists.txt

@@ -21,5 +21,3 @@ if(WIN32)
         PRE_BUILD COMMAND ${CMAKE_COMMAND} -E copy ${SFML_SOURCE_DIR}/extlibs/bin/$<IF:$<EQUAL:${CMAKE_SIZEOF_VOID_P},8>,x64,x86>/openal32.dll $<TARGET_FILE_DIR:main>
         VERBATIM)
 endif()
-
-install(TARGETS main)