srand: throw DomainError if a negative seed is used.
system_error: use symbols consistently for first arg.
allow concatenation of Strings and Chars with the * operator.
base/sysimg.jl: remove trailing whitespace.
test/file.jl: rename filename => file, dir_name => dir.
base/path.jl: new and improved path manipulation api.
Merge branch 'master' of github.com:JuliaLang/julia