also trying TDirectory

[aminnj]

attempt to support TDirectories a la #67

julia> using UnROOT

julia> f = UnROOT.samplefile("tdir_complicated.root")
ROOTFile with 3 entries and 23 streamers.
/Users/namin/.julia/dev/UnROOT/test/samples/tdir_complicated.root
├─ a (TH1F)
├─ b (TH1F)
└─ mydir
   ├─ Events (TTree)
   │  └─ "Jet_pt"
   ├─ c (TH1F)
   ├─ d (TH1F)
   └─ mysubdir
      ├─ e (TH1F)
      └─ f (TH1F)

julia> f["mydir/mysubdir/e"][:fName]
"e"

julia> f["mydir"]["mysubdir"]["e"][:fName]
"e"

julia> length.(LazyTree(f, "mydir/Events").Jet_pt) |> println
Float32[0.0, 73.067154, 0.0, 20.33066, 0.0, 0.0]

julia> sum(UnROOT.samplefile("issue11_tdirectory.root")["Data/mytree/Particle0_E"])
1012.0000000000031

[codecov]

Codecov Report

Merging #107 (68df67c) into master (b32d2cb) will increase coverage by 0.09%.
The diff coverage is 96.66%.

@@            Coverage Diff             @@
##           master     #107      +/-   ##
==========================================
+ Coverage   89.84%   89.94%   +0.09%     
==========================================
  Files          11       11              
  Lines        1319     1342      +23     
==========================================
+ Hits         1185     1207      +22     
- Misses        134      135       +1     

Impacted Files	Coverage Δ
src/root.jl	90.90% <90.00%> (-0.09%)	⬇️
src/bootstrap.jl	84.02% <100.00%> (+0.45%)	⬆️
src/displays.jl	98.11% <100.00%> (+0.15%)	⬆️

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[tamasgal]

I think this looks good, great :D

Regarding the reference propagation: we may refactor that at some point, but currently it is OK like this. We should focus on mandatory features first and at some point start to work on the internal API, whenever it gets too hacky ;)