[Eva] New module type Abstractions.Eva: all abstractions and the evaluator.

Makefile

src/plugins/value/engine/abstractions.ml

src/plugins/value/engine/abstractions.mli

src/plugins/value/engine/analysis.ml

src/plugins/value/engine/compute_functions.ml

src/plugins/value/engine/compute_functions.mli

src/plugins/value/engine/transfer_specification.ml

src/plugins/value/engine/transfer_specification.mli

src/plugins/value/engine/transfer_stmt.ml

src/plugins/value/engine/transfer_stmt.mli