Support unicode names for variables, constants and events

Created by: stephanemagnenat

The Aseba compiler is fully unicode compatible, allowing unicode characters in variable, constant and event names.

While the switch expects UTF8-encoded string values, it checks these using a dumb regex ("^[A-Za-z_][A-Za-z0-9_\.]*"), which disallows unicode characters. It does so using C++'s own regexp support. A solution to this problem is to use instead the extended regexp grammar and the [:alnum:] entry (see http://pubs.opengroup.org/onlinepubs/9699919799/basedefs/V1_chap09.html#tag_09_04). However, for this to work the switch should force the use of UTF8 locale, which is unlikely to work on Windows. A fall back would be to convert the string to wstring before running the regexp. It is probably the safest solution.