Added TransSys.input type, for representing the source data which transition systems are created from. Added one variant, LustreInput, representing input from lustre source code.

Added field input to TransSys.t called input, with type TransSys.input. This will be used
to help transform the model into a form that is understandable to the user.
Changed tree_path type to use maps rather than association lists
reorganized lustrePath. Continued writing code for reconstructing stateless variables.
finished implementing stateless variable reconstruction (have not tested yet)
Merge https://github.com/kind2-mc/kind2

Conflicts:
	src/lustrePath.ml
	src/lustrePath.mli
	src/transSys.ml
	src/transSys.mli

Merged from dev. Rewrote plaintext pretty-printing code to use new tree_path
data-type. Modified stateless variable reconstruction to inlcude node calls,
transitive reconstruction, and reconstruction from abstract and oracle streams.
Commented and cleaned up.

Added new functions to lib.ml:
-list_init
-list_zip
-list_unzip
-array_max
-pp_print_arrayi
Merge branch 'develop' of https://github.com/kind2-mc/kind2

Conflicts:
	src/lustrePath.ml
Removed the type node_prop from lustrePath.ml. I didn't think it was different enough from
LustreExpr.state_var_source to warrant having another type.
fixed path tracking for plaintext output. rewrote plaintext printing in a
non-tail recursive fashion. added "class = local" to output for local tree_path nodes.
fixed plaintext printing so that streams are printed
remove intermediate streams from plaintext output. added comments, fixed existing ones
Added header comments to uncommented functions
changed ancestors param to ancestor_idents
Improved comments on local function definitions. Removed type ascriptions from formals in order
to conform with project standards.
Moved functions to Lib and Event
Reconstruct stateless stream in countereaxamples

Conflicts:
	src/transSys.ml
	src/transSys.mli