loose compatibility bound on FixedPointNumbers for Colors and ColorType

[johnnychen94]

There are some compatibility problem upgrading to the new registrator.

Cont. #363

cc: @timholy

[johnnychen94]

ping @fredrikekre could you help merge this PR? I guess that's an approval from Tim

[fredrikekre]

I trust you have verified that this is OK?

[johnnychen94]

Yes, positive

We bump a minor version of FixedPointNumbers from 0.5 to 0.6 when upgraded to the new registrator (PR), there are no compatibility differences between these two minor versions. And Colors and ColorTypes haven't upgraded yet.

This patch helps fixes compatibility conflicts in packages that depend on both FixedPointNumbers and Colors (e.g, ImageCore and Images.jl) if they want to use master branches of Colors and FixedPointNumbers (e.g., JuliaImages/ImageCore.jl#78)

More details...

(tmp) pkg> add ImageCore
  Updating registry at `~/.julia/registries/General`
  Updating git-repo `https://github.com/JuliaRegistries/General.git`
 Resolving package versions...
  Updating `~/tmp/Project.toml`
  [a09fc81d] + ImageCore v0.8.2
  Updating `~/tmp/Manifest.toml`
  [621f4979] + AbstractFFTs v0.4.1
  [b99e7846] + BinaryProvider v0.5.4
  [3da002f7] + ColorTypes v0.7.5
  [5ae59095] + Colors v0.9.5
  [34da2185] + Compat v2.1.0
  [8f4d0f93] + Conda v1.2.0
  [7a1cc6ca] + FFTW v0.2.4
  [53c48c17] + FixedPointNumbers v0.5.3
  [a2bd30eb] + Graphics v0.4.0
  [a09fc81d] + ImageCore v0.8.2
  [682c06a0] + JSON v0.20.0
  [dbb5928d] + MappedArrays v0.2.1
  [77ba4419] + NaNMath v0.3.2
  [6fe1bfb0] + OffsetArrays v0.11.0
  [5432bcbf] + PaddedViews v0.4.2
  [189a3867] + Reexport v0.2.0
  [81def892] + VersionParsing v1.1.3
  [2a0f44e3] + Base64 
  [ade2ca70] + Dates 
  [8bb1440f] + DelimitedFiles 
  [8ba89e20] + Distributed 
  [b77e0a4c] + InteractiveUtils 
  [76f85450] + LibGit2 
  [8f399da3] + Libdl 
  [37e2e46d] + LinearAlgebra 
  [56ddb016] + Logging 
  [d6f4376e] + Markdown 
  [a63ad114] + Mmap 
  [44cfe95a] + Pkg 
  [de0858da] + Printf 
  [3fa0cd96] + REPL 
  [9a3f8284] + Random 
  [ea8e919c] + SHA 
  [9e88b42a] + Serialization 
  [1a1011a3] + SharedArrays 
  [6462fe0b] + Sockets 
  [2f01184e] + SparseArrays 
  [10745b16] + Statistics 
  [8dfed614] + Test 
  [cf7118a7] + UUIDs 
  [4ec0a83e] + Unicode 

(tmp) pkg> add Colors#master
  Updating git-repo `https://github.com/JuliaGraphics/Colors.jl.git`
 Resolving package versions...
  Updating `~/tmp/Project.toml`
  [5ae59095] + Colors v0.9.4 #master (https://github.com/JuliaGraphics/Colors.jl.git)
  Updating `~/tmp/Manifest.toml`
  [5ae59095] ~ Colors v0.9.5 ⇒ v0.9.4 #master (https://github.com/JuliaGraphics/Colors.jl.git)

(tmp) pkg> add FixedPointNumbers#master
  Updating git-repo `https://github.com/JuliaMath/FixedPointNumbers.jl.git`
 Resolving package versions...
ERROR: Unsatisfiable requirements detected for package FixedPointNumbers [53c48c17]:
 FixedPointNumbers [53c48c17] log:
 ├─possible versions are: 0.6.0 or uninstalled
 ├─restricted to versions * by Colors [5ae59095], leaving only versions 0.6.0
 │ └─Colors [5ae59095] log:
 │   ├─possible versions are: 0.9.4 or uninstalled
 │   └─Colors [5ae59095] is fixed to version 0.9.4
 ├─FixedPointNumbers [53c48c17] is fixed to version 0.6.0
 └─found to have no compatible versions left with ColorTypes [3da002f7] 
   └─ColorTypes [3da002f7] log:
     ├─possible versions are: [0.0.1, 0.1.0-0.1.7, 0.2.0-0.2.12, 0.3.0-0.3.5, 0.4.0-0.4.1, 0.5.0-0.5.2, 0.6.0-0.6.7, 0.7.0-0.7.5] or uninstalled
     ├─restricted to versions * by Colors [5ae59095], leaving only versions [0.0.1, 0.1.0-0.1.7, 0.2.0-0.2.12, 0.3.0-0.3.5, 0.4.0-0.4.1, 0.5.0-0.5.2, 0.6.0-0.6.7, 0.7.0-0.7.5]
     │ └─Colors [5ae59095] log: see above
     ├─restricted by julia compatibility requirements to versions: 0.7.0-0.7.5 or uninstalled, leaving only versions: 0.7.0-0.7.5
     └─restricted by compatibility requirements with ImageCore [a09fc81d] to versions: 0.7.5
       └─ImageCore [a09fc81d] log:
         ├─possible versions are: [0.0.1-0.0.5, 0.1.0-0.1.5, 0.2.0-0.2.1, 0.3.0-0.3.3, 0.4.0-0.4.1, 0.5.0, 0.6.0, 0.7.0-0.7.4, 0.8.0-0.8.2] or uninstalled
         └─restricted to versions 0.8.2 by an explicit requirement, leaving only versions 0.8.2