Export marker

If a declared symbol is marked with an asterisk it is exported from the current module:

proc exportedEcho*(s: string) = echo s
proc `*`*(a: string; b: int): string =
  result = newStringOfCap(a.len * b)
  for i in 1..b: result.add a
var exportedVar*: int
const exportedConst* = 78
type
  ExportedType* = object
    exportedField*: int