Adjust formatting, add entry in NEWS.md.

Some small fixes in range.jl and conversion.jl.

NEWS.md

@@ -1,6 +1,7 @@
 - v0.1.5
   - Patch for Julia PR [#20889](https://github.com/JuliaLang/julia/pull/20889), which changes how lowering is done for exponentiation of integer literals.
   - Bug fix to enable registering Main as a module for `u_str` (fixes [#61](https://github.com/ajkeller34/Unitful.jl/issues/61)).
+  - Implement readable message for `DimensionError` [#62](https://github.com/ajkeller34/Unitful.jl/pull/62).
 - v0.1.4
   - Critical bug fix owing to `mod_fast` changes.
 - v0.1.3

src/Conversion.jl

@@ -47,7 +47,7 @@ Find the conversion factor from unit `t` to unit `s`, e.g. `convfact(m,cm) = 0.0
     # Check if conversion is possible in principle
     sdim = dimension(s())
     tdim = dimension(t())
-    sdim != tdim && throw(DimensionError(s,t))
+    sdim != tdim && throw(DimensionError(s(),t()))
 
     # first convert to base SI units.
     # fact1 is what would need to be multiplied to get to base SI units

src/Unitful.jl

@@ -54,13 +54,16 @@ type DimensionError{T,S} <: Exception
   y::S
 end
 ```
-Thrown when dimensions don't match in an operation that demands they do. Display `x` and `y` in error message.
+
+Thrown when dimensions don't match in an operation that demands they do.
+Display `x` and `y` in error message.
 """
 type DimensionError{T,S} <: Exception
-  x::T
-  y::S
+    x::T
+    y::S
 end
-Base.showerror(io::IO, e::DimensionError) = print(io,"DimensionError: $(e.x) and $(e.y) are not dimensionally compatible.");
+Base.showerror(io::IO, e::DimensionError) =
+    print(io,"DimensionError: $(e.x) and $(e.y) are not dimensionally compatible.");
 
 """
 ```

src/range.jl

@@ -10,18 +10,18 @@
     linspace(Float64, ustrip(start), ustrip(stop), len, 1)*unit(T)
 
 function _linspace{T}(start::Quantity{T}, stop::Quantity{T}, len::Integer)
-    dimension(start) != dimension(stop) && throw(DimensionError())
+    dimension(start) != dimension(stop) && throw(DimensionError(start, stop))
     linspace(start, stop, len)
 end
 
 @compat function colon(start::Quantity{<:Real}, step, stop::Quantity{<:Real})
-    dimension(start) != dimension(stop) && throw(DimensionError())
+    dimension(start) != dimension(stop) && throw(DimensionError(start, stop))
     T = promote_type(typeof(start),typeof(stop))
     return colon(convert(T,start), step, convert(T,stop))
 end
 
 function colon(start::A, step::B, stop::A) where A<:Quantity{<:Real} where B<:Quantity{<:Real}
-    dimension(start) != dimension(step) && throw(DimensionError())
+    dimension(start) != dimension(step) && throw(DimensionError(start, step))
     colon(promote(start, step, stop)...)
 end