Remove invalid URLs

Merge pull request #155 from munterfi/bugfix/cran-resubmission

Prepare resubmission

Update roxygen.

Adjust test.

Merge pull request #144 from munterfi/release/v0.8.1

Merge pull request #141 from munterfinger/release/v0.8.0

Release/v0.8.0

Merge pull request #134 from munterfinger/release/v0.7.1

Release/v0.7.1

Merge pull request #126 from munterfinger/release/v0.7.0

Release/v0.7.0

Merge pull request #115 from munterfinger/release/v0.6.1

Release/v0.6.1

Merge pull request #107 from munterfinger/release/v0.6.0

Release/v0.6.0