small tweaks to printing

src/GroupRings.jl

@@ -208,9 +208,9 @@ function show(io::IO, X::GroupRingElem)
    elseif isdefined(RG, :basis)
       non_zeros = ((X.coeffs[i], RG.basis[i]) for i in findn(X.coeffs))
       elts = ("$(sign(c)> 0? " + ": " - ")$(abs(c))*$g" for (c,g) in non_zeros)
-      str = join(elts, "")
+      str = join(elts, "")[2:end]
       if sign(first(non_zeros)[1]) > 0
-         str = str[4:end]
+         str = str[3:end]
       end
       print(io, str)
    else

test/runtests.jl

@@ -77,7 +77,8 @@ using Nemo
       @test a[5] == 1
       @test a[p] == 1
 
-      @test string(a) == " + 1*[2, 3, 1]"
+      @test string(a) == "1*[2, 3, 1]"
+      @test string(-a) == "- 1*[2, 3, 1]"
 
       @test RG([0,0,0,0,1,0]) == a
 
@@ -89,7 +90,8 @@ using Nemo
       @test a[1] == 2
       @test a[s] == 2
 
-      @test string(a) == " + 2*[1, 2, 3] + 1*[2, 3, 1]"
+      @test string(a) == "2*[1, 2, 3] + 1*[2, 3, 1]"
+      @test string(-a) == "- 2*[1, 2, 3] - 1*[2, 3, 1]"
 
       @test length(a) == 2
    end