Add doc_str and doc macros, to support Base.Docs/Docile syntax.

Author: hayd

README.md

@@ -109,6 +109,8 @@ Currently, the `@compat` macro supports the following syntaxes:
 
 * `@inline` and `@noinline` have been added. On 0.3, these are "no-ops," meaning they don't actually do anything.
 
+* `@doc`, `@doc_str` and `@doc_mstr` have been added. On 0.3 if Docile is available it will use its definitions, else these are no-ops.
+
 ## Other changes
 
 * `Dict(ks, vs)` is now `Dict(zip(ks, vs))` [#8521](https://github.com/JuliaLang/julia/pull/8521)

src/Compat.jl

@@ -38,6 +38,16 @@ if VERSION < v"0.4.0-dev+412"
     eval(Base, :(const IPAddr = IpAddr))
 end
 
+if VERSION < v"0.4.0-dev+1501"
+    try
+        import Docile: @doc_str, @doc_mstr, @doc
+    catch
+        macro doc_str(x) x end
+        macro doc_mstr(x) x end
+        macro doc(ex) esc(ex.args[end]) end
+    end
+end
+
 if VERSION < v"0.4.0-dev+2197"
     Base.IPv4(ipstr::AbstractString) = Base.parseipv4(ipstr)
     Base.IPv6(ipstr::AbstractString) = Base.parseipv6(ipstr)