Remove use of automatic adjacent string literal concatenation from phobos
Fix wrong test
replace use of deprecated canFind overload

- !canFind(not!isDigit) == all!isDigit
Merge pull request #1876 from MartinNowak/canFind

replace use of deprecated canFind overload
Merge pull request #1871 from yebblies/stringcat

Remove use of automatic adjacent string literal concatenation from phobos