Fixed name of patch file for ATTIny4313 header
Added patch for ATTiny2313 header.
Updated Xcode project to reflect new patch names.
Disable stack protector.

Gcc built with Xcode 5 aborts with a stack protection failure when compiling libgcc for avrtiny. This is a bug in either of the two compilers.
Do not load FreeBSD patches any more.

Patches for the current compiler versions are not available anyway.
Remove all dependent files before compiling gcc.

Since patches apply to the original source files only, all dependent files must be forced to be rebuilt.
Do not retry make if first attempt fails.

This was a workaround which is no longer required.
Suppress -Werror when compiling simulavr.

Xcode 5 has more warnings, which let the build of simulavr fail when -Werror is active.
Do not check whether avr-gcc-nm etc can be executed successfully.

Since we do not compile with plugin-support, these tools always fail.
Do not automatically tag release in git.

Tagging is better done manually when a real release is made.
Updated versions
Refer to Xcode 5 in Readme
Describe how mkdist.sh is run in debug mode.
Updated release notes.
Header patch is for ATTiny2313A, not ATTiny2313
Removed remainings from FreeBSD patches.