Add i18n for default friend request text
Introduce STRING_INIT helper to sized_string.h
Reserve 0 for invalid UI_STRING_ID
Introduce MAYBE_I18NAL_STRING struct to ui.h
Convert dropdowns to use MAYBE_I18NAL_STRING
Add i18n text for edit box hints
Rewrite edit box hints with i18n support
Add russian-localized text for friend request
Add russian-localized text for edit hints
Merge branch 'i18n-for-friend-request-and-edit-hints' of https://github.com/albel727/uTox

#
# Please enter a commit message to explain why this merge is necessary,
# especially if it merges an updated upstream into a topic branch.
#
# Lines starting with '#' will be ignored, and an empty message aborts
# the commit.
Italian translation: update
Merge pull request #521 from Ansa89/italian-translation

Italian translation: update
fix a merge conflict

Conflicts:
	langs/pl.h