Merge pull request #12 from RLado/generics

Version bump to v1.2.0

Fix overloaded operators (+, -, *) T 'op' Sprs<T> to work with the new generic implementation

Restored tests for overloaded operators (+, -, *) `T` 'op' `Sprs<T>`

Update test utils

Fixed consistency of `std::ops` usage

Update README to reflect the use of generics

Implemented generics for `Sprs`

Version bump to v1.1.0

Merge pull request #11 from Masterchef365/master

Unwrap() in solver tests

Use an enum for the error type

Turn panic!() into Err(String)

Update CITATION.cff

Minor README fix