Tgedmd reweighting

[fnueske]

Improved and re-structured tgEDMD implementation, updated examples, minor changes to transform and utils.

• Introduced re-weighting option for tgedmd.
• new efficient implementation of reversible and non-reversible tgedmd.
• updated lemon slice and deca alanine examples.
• implemented second derivatives for Gaussian basis set in data_driven/transform
• new option to choose between relative or absolute singular value truncation in solves/utils/truncated_svd