nls: add compose seq's for ASCII symbols absent from Cyrillic layouts to ru_RU

JCUKEN (ЙЦУКЕН) - the default and de-facto standard layout for most Cyrillic scripts - lacks a number of ASCII symbols from the QWERTY counterpart, forcing users to switch back-and-forth between layouts to type them.

This patch adds sequences for them to the ru_RU compose map in an intuitive and consistent manner.

Fixes #200 (closed) for ru_RU (but other Cyrillic layouts might benefit too)