* added iOS 7.0, ARM64 and OpenGL ES 3.0 support:
   * concerning gl_support: all of the OpenGL ES 2.0 defines/aliases are unnecessary as these are all available in OpenGL ES 3.0 "core" (except glClearDepth which still aliases to glClearDepthf)
   * added more OpenGL ES 2.0 aliases (multi-sampled renderbuffer and buffer mapping functions, and fbo attachments/formats/types)
   * floors data_path is a relative path on iOS (absolute paths are too problematic with iOSs sandbox)
   * added ios_helper class (get_dpi, get_system_version, get_compiled_system_version and some "internal" shader functionality)
   * updated OpenCL code for iOS (computes and sets the IOS_VERSION_COMPILED and IOS_VERSION defines)
   * note that a static lib is build for iOS and no dependency libraries are linked (these have to be linked in the final .app project: -lSDL2 -lfloor -lcrypto -lssl -framework OpenCL; OpenCL only for iPhoneOS)
   * for build instructions look at the updated README
 * added new const_string class that is actually functional thanks to c++14 (currently supports string concatenation and ==/!= comparisons; const_strings can be constructed via "make_const_string", "CS(str)" and with a "_cs" UDL for number literals)
 * added the possibility to disable OpenCL by setting the FLOOR_NO_OPENCL flag (note: this is set when compiling for the iPhoneSimulator, because the OpenCL framework is a private framework that the simulator doesn't provide - the iPhoneOS SDK however does provide it and OpenCL is functional on iOS devices!)
 * renamed cl.hpps cl::Error to cl::Err due to weird linking issues
 * added file_io get_swapped_uint and get_swapped_usint functions (reads an unsigned (short) int in little endian)
 * the length parameter of file_io::get_line should be of type streamsize
 * marked enum_class_bitwise_or and enum_class_bitwise_and friend functions constexpr
 * added new enum_class_bitwise_or_global and enum_class_bitwise_and_global + resp. *_impl macros (the former should be used in the header, the latter should be used in a cpp file)
 * disabled XML validation on iOS for now (due to misc issues)
 * check for OpenGL errors (glGetError) before calling swap() (in floor::stop_draw)
 * define rename: PLATFORM_X86 -> PLATFORM_X32 (this obviously makes more sense; note that this change concerns all floor build tools and all projects depending on floor -> these will be updated later)
 * improved xcode project file (rely more on $(inherited); updated X11 path for OS X)
 * updated the README with iOS info
 * added version checks for libc++, SDL2 and OpenSSL (in floor_version.hpp)
 * version bump to v0.1.1-d1