calculate support for arabic numbers

[javedkhan]

Creating support for Arabic numbers۰۱۲۳۴۵۶۷۸۹(for Pashto and Dari) in the interface and the entered text in Calculate Activity.

[cjl]

I beleive gettext can help with this by using %Id in place of %d when translating the UI strings into Arabic. I'm not sure how much work is needed on the backend.

 http://www.gnu.org/software/gettext/manual/gettext.html#c_002dformat

"As a special feature for Farsi (Persian) and maybe Arabic, translators can insert an ‘I’ flag into numeric format directives. For example, the translation of "%d" can be "%Id". The effect of this flag, on systems with GNU libc, is that in the output, the ASCII digits are replaced with the ‘outdigits’ defined in the LC_CTYPE locale category. On other systems, the gettext function removes this flag, so that it has no effect.

Note that the programmer should not put this flag into the untranslated string. (Putting the ‘I’ format directive flag into an msgid string would lead to undefined behaviour on platforms without glibc when NLS is disabled.)"