should be updated for julia 0.6

[CarloLucibello]

currently it fails to precompile on 0.6

ulia> using AutoGrad
INFO: Recompiling stale cache file /home/carlo/.julia/lib/v0.6/AutoGrad.ji for module AutoGrad.

WARNING: deprecated syntax "typealias Tape Vector{Node}" at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:294.
Use "const Tape = Vector{Node}" instead.
WARNING: Array{T}(::Type{T}, m::Int) is deprecated, use Array{T}(m) instead.
Stacktrace:
 [1] depwarn(::String, ::Symbol) at ./deprecated.jl:64
 [2] Array(::Type{AutoGrad.Node}, ::Int64) at ./deprecated.jl:51
 [3] #Rec#10(::Function, ::Tuple{}, ::Array{Any,1}, ::Type{T} where T, ::Void, ::Array{AutoGrad.Node,1}) at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:307
 [4] AutoGrad.Rec(::Void) at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:307
 [5] include_from_node1(::String) at ./loading.jl:539
 [6] include(::String) at ./sysimg.jl:14
 [7] include_from_node1(::String) at ./loading.jl:539
 [8] include(::String) at ./sysimg.jl:14
 [9] anonymous at ./<missing>:2
 [10] eval(::Module, ::Any) at ./boot.jl:235
 [11] process_options(::Base.JLOptions) at ./client.jl:286
 [12] _start() at ./client.jl:371
while loading /home/carlo/.julia/v0.6/AutoGrad/src/core.jl, in expression starting on line 329
WARNING: Array{T}(::Type{T}, m::Int) is deprecated, use Array{T}(m) instead.
Stacktrace:
 [1] depwarn(::String, ::Symbol) at ./deprecated.jl:64
 [2] Array(::Type{AutoGrad.Node}, ::Int64) at ./deprecated.jl:51
 [3] Type at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:289 [inlined]
 [4] #Rec#10(::Function, ::Tuple{}, ::Array{Any,1}, ::Type{T} where T, ::Void, ::Array{AutoGrad.Node,1}) at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:308
 [5] AutoGrad.Rec(::Void) at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:307
 [6] include_from_node1(::String) at ./loading.jl:539
 [7] include(::String) at ./sysimg.jl:14
 [8] include_from_node1(::String) at ./loading.jl:539
 [9] include(::String) at ./sysimg.jl:14
 [10] anonymous at ./<missing>:2
 [11] eval(::Module, ::Any) at ./boot.jl:235
 [12] process_options(::Base.JLOptions) at ./client.jl:286
 [13] _start() at ./client.jl:371
while loading /home/carlo/.julia/v0.6/AutoGrad/src/core.jl, in expression starting on line 329
WARNING: Array{T}(::Type{T}, m::Int) is deprecated, use Array{T}(m) instead.
Stacktrace:
 [1] depwarn(::String, ::Symbol) at ./deprecated.jl:64
 [2] Array(::Type{AutoGrad.Node}, ::Int64) at ./deprecated.jl:51
 [3] AutoGrad.Node(::AutoGrad.Rec{Void}) at /home/carlo/.julia/v0.6/AutoGrad/src/core.jl:289
 [4] include_from_node1(::String) at ./loading.jl:539
 [5] include(::String) at ./sysimg.jl:14
 [6] include_from_node1(::String) at ./loading.jl:539
 [7] include(::String) at ./sysimg.jl:14
 [8] anonymous at ./<missing>:2
 [9] eval(::Module, ::Any) at ./boot.jl:235
 [10] process_options(::Base.JLOptions) at ./client.jl:286
 [11] _start() at ./client.jl:371
while loading /home/carlo/.julia/v0.6/AutoGrad/src/core.jl, in expression starting on line 329

WARNING: deprecated syntax "typealias D1 Type{Grad{1}}" at /home/carlo/.julia/v0.6/AutoGrad/src/util.jl:325.
Use "const D1 = Type{Grad{1}}" instead.

WARNING: deprecated syntax "typealias D2 Type{Grad{2}}" at /home/carlo/.julia/v0.6/AutoGrad/src/util.jl:326.
Use "const D2 = Type{Grad{2}}" instead.

WARNING: deprecated syntax "typealias Dn{N} Type{Grad{N}}" at /home/carlo/.julia/v0.6/AutoGrad/src/util.jl:328.
Use "Dn{N} = Type{Grad{N}}" instead.
ERROR: LoadError: LoadError: UndefVarError: decolon not defined
Stacktrace:
 [1] include_from_node1(::String) at ./loading.jl:539
 [2] include(::String) at ./sysimg.jl:14
 [3] include_from_node1(::String) at ./loading.jl:539
 [4] include(::String) at ./sysimg.jl:14
 [5] anonymous at ./<missing>:2
while loading /home/carlo/.julia/v0.6/AutoGrad/src/interfaces.jl, in expression starting on line 99
while loading /home/carlo/.julia/v0.6/AutoGrad/src/AutoGrad.jl, in expression starting on line 18
ERROR: Failed to precompile AutoGrad to /home/carlo/.julia/lib/v0.6/AutoGrad.ji.
Stacktrace:
 [1] compilecache(::String) at ./loading.jl:673
 [2] require(::Symbol) at ./loading.jl:431

[denizyuret]

Latest master is Julia6 compatible.