refactor: import and utilise RSpectra::svds() instead of base::svd().

svds() only calculates the required number of left and right singular vector as eigenvalues. svd() calculates an excessive amount which can cause runtime inflation for large datasets

refactor: import and utilise RSpectra::svds() instead of base::svd(). This is now also applied to spca()

docs: updated NAMESPACE and DESCRIPTION to include new dependency

docs: updated DESCRIPTION with new import

tests: increased suffix length in `plotLoadings()` label-length check

refactor: import and utilise RSpectra::svds() instead of base::svd().

svds() only calculates the required number of left and right singular vector as eigenvalues. svd() calculates an excessive amount which can cause runtime inflation for large datasets

refactor: import and utilise RSpectra::svds() instead of base::svd(). This is now also applied to spca()

docs: updated NAMESPACE and DESCRIPTION to include new dependency

docs: updated DESCRIPTION with new import

fix: when ILR/CLR was used, X was of invalid class. Added check to ensure `svds()` can operate on X

…into issue-250

fix: when ILR/CLR was used, X was of invalid class. Added check to ensure `svds()` can operate on X. Implemented this for `spca()`