Issue 288 more password characters

Use [a technique](https://developer.mozilla.org/en-US/docs/Web/JavaScript/Reference/Global_Objects/String/charCodeAt#Example_2.3A_Fixing_charCodeAt_to_handle_non-Basic-Multilingual-Plane_characters_if_their_presence_earlier_in_the_string_is_unknown) for consolidating multi-char representation of non-basic multilingual characters, to reconstruct the entered characters from browsers (including the Android webview widget) that separate them on input.

Proven successfully on the desktop browser, Nexus 7 (4.2.2) and Samsung
galaxy S3 (4.1.2), with an account with a password including spaces,
url-encoding-sensitive ascii ("&"), and a btoa-breaking multi-lingual
character from each of hebrew ("ש") and chinese/japanese ("日"): t & ש 日