Minor exception display changes.

Author: maleadt

src/device/cuda/atomics.jl

@@ -303,6 +303,9 @@ struct AtomicError <: Exception
     msg::AbstractString
 end
 
+Base.showerror(io::IO, err::AtomicError) =
+    print(io, "AtomicError: ", err.msg)
+
 """
     @atomic a[I] = op(a[I], val)
     @atomic a[I] ...= val

src/exceptions.jl

@@ -10,8 +10,6 @@ function Base.showerror(io::IO, err::KernelException)
     print(io, "KernelException: exception thrown during kernel execution on device $(CUDAdrv.name(err.dev))")
 end
 
-Base.show(io::IO, err::KernelException) = print(io, "KernelException($(err.dev))")
-
 
 ## exception handling