Create base64-string.js

Transforms from base64 to/from a string where all 16 bits are used (much smaller by a factor of 16/6). This is *not* a base64 decoder.
Added versionning
Stable enough to be released
Stable enough to be released
Stable enough to be released
Create lz-string-1.2.0.js

v1.2.0 includes a compression and decompression from/to a base64-encoded string.
Rename lz-string-1.2.0.js to lz-string-1.2.0-rc1.js
Merge remote-tracking branch 'upstream/master'