Extending technology mapping and rewriting

[aletempiac]

This PR includes several updates:

• A novel technology mapping algorithm called emap that supports multi-output cells (the current version is limited to 2-output cells)
• An algorithm called extract_adders to extract half and full adders from a circuit (by circuit analysis)
• A new network type block_network that supports multi-output nodes
• A method to compute don't care classes in exact_library to support mapping using Boolean don't cares
• An extension in map and rewrite to leverage satisfiability don't cares
• New utils for pattern matching given a technology library, struct_library
• A view called cell_view to represent mapped networks. Differently from binding_view, cell_view supports multi-output cells
• A view called don't_touch_view to select gates to be preserved during optimization or mapping
• Various infrastructure to support the aforementioned changes
• Generic fixes: choice_view compatibility with klut_network, bug fix in windows_utils, and buffer overflow fix in cuts

[codecov-commenter]

Codecov Report

Merging #623 (e28b810) into master (82fce07) will decrease coverage by 0.60%. The diff coverage is 75.66%.

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@@            Coverage Diff             @@
##           master     #623      +/-   ##
==========================================
- Coverage   84.27%   83.68%   -0.60%     
==========================================
  Files         178      185       +7     
  Lines       24894    28840    +3946     
==========================================
+ Hits        20980    24135    +3155     
- Misses       3914     4705     +791     

Files	Coverage Δ
...nclude/mockturtle/algorithms/experimental/emap.hpp	81.41% <ø> (ø)
include/mockturtle/networks/klut.hpp	94.50% <100.00%> (+0.08%)	:arrow_up:
include/mockturtle/networks/storage.hpp	97.61% <ø> (ø)
include/mockturtle/utils/algorithm.hpp	92.68% <100.00%> (+6.31%)	:arrow_up:
include/mockturtle/utils/cuts.hpp	91.22% <100.00%> (ø)
include/mockturtle/utils/standard_cell.hpp	100.00% <100.00%> (ø)
include/mockturtle/views/choice_view.hpp	77.77% <100.00%> (+2.02%)	:arrow_up:
include/mockturtle/views/dont_touch_view.hpp	100.00% <100.00%> (ø)
include/mockturtle/utils/window_utils.hpp	93.41% <50.00%> (-0.27%)	:arrow_down:
include/mockturtle/views/cell_view.hpp	96.82% <96.82%> (ø)
... and 7 more

... and 4 files with indirect coverage changes