WIP: handle NotInstalledError

[johnnychen94]

From previous PR #76 this feature looks like supported, but I can't find the commit that deprecates this. And looks like NotInstalledError isn't used anymore.

I'll work on test cases if this feature is needed, otherwise, I'll close this PR and clean error_handling.jl in next PR.

before:

julia> using TestImages
[ Info: Recompiling stale cache file /home/math/jc/.julia/compiled/v1.1/TestImages/cMlD2.ji for TestImages [5e47fb64-e119-507b-a336-dd2b206d9990]

julia> testimage("ca")
Error encountered while loading "/home/math/jc/.julia/packages/TestImages/6bT9D/images/cameraman.tif".
Fatal error:
ERROR: ArgumentError: Package ImageMagick not found in current path:
- Run `import Pkg; Pkg.add("ImageMagick")` to install the ImageMagick package.

Stacktrace:
 [1] handle_error(::ArgumentError, ::FileIO.File{FileIO.DataFormat{:TIFF}}) at /home/math/jc/.julia/packages/FileIO/e8FNK/src/error_handling.jl:80
 [2] handle_exceptions(::Array{Any,1}, ::String) at /home/math/jc/.julia/packages/FileIO/e8FNK/src/error_handling.jl:75
 [3] #load#27(::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::Function, ::FileIO.File{FileIO.DataFormat{:TIFF}}) at /home/math/jc/.julia/packages/FileIO/e8FNK/src/loadsave.jl:193
 [4] load(::FileIO.File{FileIO.DataFormat{:TIFF}}) at /home/math/jc/.julia/packages/FileIO/e8FNK/src/loadsave.jl:172
 [5] #load#13(::Base.Iterators.Pairs{Union{},Union{},Tuple{},NamedTuple{(),Tuple{}}}, ::Function, ::String) at /home/math/jc/.julia/packages/FileIO/e8FNK/src/loadsave.jl:118
 [6] load at /home/math/jc/.julia/packages/FileIO/e8FNK/src/loadsave.jl:118 [inlined]
 [7] testimage(::String) at /home/math/jc/.julia/packages/TestImages/6bT9D/src/TestImages.jl:88
 [8] top-level scope at none:0

after:

julia> using TestImages
[ Info: Recompiling stale cache file /home/math/jc/.julia/compiled/v1.1/TestImages/cMlD2.ji for TestImages [5e47fb64-e119-507b-a336-dd2b206d9990]

julia> testimage("ca")
Error encountered while loading "/home/math/jc/.julia/packages/TestImages/6bT9D/images/cameraman.tif".
Fatal error:
Library "ImageMagick" is not installed but is recommended as a library to load format: ".tif"
Should we install "ImageMagick" for you? (y/n):

[johnnychen94]

Close this since there's no additional feedback. I'm not sure if this is a wanted feature.

[timholy]

It may just be that no one got around to reviewing this; certainly I was quite busy when it was first submitted (still am, but...). I have a vague memory that @SimonDanisch might have disabled this out of fears that it was too magical?

[SimonDanisch]

There was a lot of push back against this and since it was breaking on 1.0, I removed it - or maybe someone else who took up porting FileIO to 1.0 did ;)
But I'm actually quite happy with it removed, since I usually run into an uninstalled package in Atom, which would freeze my julia process (no prompt, but still isinteractive() == true)

[johnnychen94]

In this case, shall I clean the legacy file error_handling.jl?

[timholy]

I'm not sure I've seen the Pkg.add feature run in ages, so I'd be happy having it removed.