0.8.0 release

Added
- Documentation of the specification of the library
- Evaluation of polynomial and transfer functions now take reference
values too
- Add polynomial creation from iterators
- AsRef trait to polynomial for reference-to-reference conversion into a
slice
- decibel unit of measurement
- Polynomial round off to zero
- Conversion from TfGen to SSGen using controllability canonical form
- Methods to check transfer function stability
- Auto implementation of PartialEq trait for SSGen
- Auto implementation Clone trait for TfGen and SSGen
- Methods to check transfer functions stability
Changed
- Improvements on polynomial roots finders and increment of related
tests
- General source code linting
- Use IntoIterator trait as interface in methods that require an
iterator
- Evaluation of polynomials and transfer functions now can take
references
- Polynomial numeric type no longer requires Copy trait
API Changes
- Changed iterator names (C-ITER-TY API guidelines)
- Changed linear system solvers names (C-ITER-TY API guidelines)
- Changed linear system evolution iterators names (C-ITER-TY API
guidelines)
- Changed arma iterators names (C-ITER-TY API guidelines)
- Renamed Decibel trait to ToDecibel
- Moved Discretization to top module
- Removed Eval trait
- Removed TryFrom trait from TfGen
- Moved the implementation of the polynomial matrices to its own module
Fixed
- Subtraction between a real number and a polynomial
- Derivation of zero degree polynomial
- Conversion from transfer function to state space representation
- Derivation of zero degree polynomials