arm64 support
Merge pull request #9 from BillinghamJ/issue-#9

arm64 support
Fix SIGSEGV when encoding 1- or 2-byte data

Fix bug introduced by 4062db26 (arm64 support), which switched from signed to unsigned counters. It broke the for loop for small inputLength, since the comparison we did (0 < 1lu - 2lu) required signed integers.
Merge pull request #11 from yonran/fix-segfault-with-small-data

Fix SIGSEGV when encoding 1- or 2-byte data
Updated README to reflect iOS changes
Merge branch 'master' of https://github.com/nicklockwood/Base64
Updated to version 1.2