Added install option to CMake

CMakeLists.txt

 project(xtc-length)
+cmake_minimum_required(VERSION 2.8)
 
 if("${CMAKE_C_COMPILER_ID}" STREQUAL "GNU")
     set(CMAKE_C_FLAGS "${CMAKE_C_FLAGS} -std=gnu90")
 endif()
 
 add_executable(xtc-length xtc-length.c)
+
+install(TARGETS xtc-length RUNTIME DESTINATION ${CMAKE_INSTALL_PREFIX}/bin)

README.md

@@ -5,7 +5,9 @@ This program reads the number of frames in a Gromacs XTC file, the number of ato
 ## To Compile
 From the directory where the project was downloaded:
 
-`cmake .; make`
+`cmake .; make install`
+
+If you with to install to a directory other than default use `cmake . -DCMAKE_INSTALL_PREFIX=<directory>`
 
 Since there is only one source file it is also possible to call the compiler directly if you prefer: