v0.2.7

This release:

• #109 Allow sanitizing molecules when removing hydrogens in data loading (kudos to @JoshuaMeyers)
• #114 Allow configuring normalization for GCN and GCNPredictor
• #116 #118 #128 #129 #131 #135 Fix for rexgen (kudos to @mar-volk)
• #120 #121 #122 Neural Fingerprint
• #110 Allow GNN pre-training for attribute masking and supervised learning (kudos to @wenx00)
• #133 Add timestep in early stopping
• #138 #139 PAGTN (kudos to @VIGNESHinZONE)
• #141 Fix for JTVAE