make read and load import the IO library

This implies, that all IO libraries shouldn't export their load and save
functions, so they don't extend the FileIO functions anymore. This is a
bigger change, but it seems to solve our `Lib A, Lib B can load/save the
same format` problem nicely. It still works for libraries that overload,
but we should ultimately make the change.

Author: SimonDanisch

src/FileIO.jl

@@ -55,8 +55,8 @@ function load(s::@compat(Union{AbstractString,IO}), args...; options...)
     last_exception = ErrorException("No library available to load $s")
     for library in libraries
         try
-            check_loader(library)
-            return load(q, args...; options...)
+            Library = check_loader(library)
+            return Library.load(q, args...; options...)
         catch e
             last_exception = e
         end
@@ -76,8 +76,8 @@ function save(s::@compat(Union{AbstractString,IO}), data...; options...)
     last_exception = ErrorException("No library available to save $s")
     for library in libraries
         try
-            check_saver(library)
-            return save(q, data...; options...)
+            Library = check_saver(library)
+            return Library.save(q, data...; options...)
         catch e
             last_exception = e #TODO, better and standardized exception propagation system
         end

src/loadsave.jl

@@ -6,9 +6,9 @@ for (appl,fchk,fadd,dct) in ((:applicable_loaders, :check_loader, :add_loader, :
     @eval begin
         $appl{sym}(::Formatted{DataFormat{sym}}) = get($dct, sym, [:nothing])
         function $fchk(pkg::Symbol)
-            if !isdefined(Main, pkg)
-                eval(Main, Expr(:using, pkg))
-            end
+            pkg == :nothing && return FileIO #nothing is the symbol for no load/save specific lib. see above
+            !isdefined(Main, pkg) && eval(Main, Expr(:import, pkg))
+            return Main.(pkg)
         end
         function $fadd{sym}(::Type{DataFormat{sym}}, pkg::Symbol)
             list = get($dct, sym, Symbol[])