Fix build warnings on 32bits archs.

Use intermediate type intptr_t for conversions between pointer
types and jlong.
Move Java build rules in a separate cmake file.
Set cmake_minimum_version for the Java bindings.

UseJava.cmake don't exist before cmake 2.8.6.
Set correct NATIVE folder for 32bits x86.
document that the search function on dynar don't work well with pointed values
document that it's safe to interrupt a foreach with a break or return statement
Typos: binded -> bound.
add another word about the trap of dynar_search with pointed elements