[C API] Add LLVMConstRealGetDouble to get the double value of a constantFP.
[OCaml] Add float_of_const to get the double value of a constantFP.
[C Api] Add various functions for terminator and branch instructions.
[OCaml] Add various functions for terminator and branch instructions.
[OCaml] Add utilities functions related to terminator and branches.
[OCaml] Add tests for floating constants and comparisons reading functions.