Leidenalg

**Changes**
* README changes, documentation changes to better document new functions from Yichen Wang (U. Michigan) in v1.1.1: https://github.com/kharchenkolab/leidenAlg/releases/tag/1.1.1

**Changes**
* Yichen Wang (U. Michigan) added functions `find_partition_with_rep()` and `find_partition_with_rep_rcpp()`

Fixed /src/leidenalg/include/MutableVertexPartition.h, Fedora-related 'GLIBCXX_ASSERTIONS' error

* Remove 'Matrix.utils' as dependency

* Install rigraph directly in `/src`. Remove previous linking to `igraph` R package in Makevars.

* Fixed Makevars to use `install_name_tool -change`.