allow symfony 5

Allow passing arbitrary additional options to MergeRequests#create()

Revert "Add method to retrieve all members from projects (including i…

…nherited)"

This reverts commit 553fab6.

Add routes to manage group boards

Support of Discussion API for issues and merge requests

(fix tests)

Merge pull request GitLabPHP#331 from woodylan/master

support impersonation tokens

iid instead of id in issue contruct

Bumped branch alias

Merge pull request GitLabPHP#297 from m-bymike/master

fix issues with symfony options resolver

Merge pull request GitLabPHP#276 from b0nd0/master

Branches containing a slash break v4 branch endpoints. GitLabPHP#263