Reorganize files; document some methods

src/solution/write.jl

@@ -0,0 +1,10 @@
+# UnitCommitment.jl: Optimization Package for Security-Constrained Unit Commitment
+# Copyright (C) 2020, UChicago Argonne, LLC. All rights reserved.
+# Released under the modified BSD license. See COPYING.md for more details.
+
+function write(filename::AbstractString, solution::AbstractDict)::Nothing
+    open(filename, "w") do file
+        return JSON.print(file, solution, 2)
+    end
+    return
+end