Schedule 4 Spellcasting not Preparing correct # of Spells

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Describe the bug
Custom classes set up with Schedule 4 spellcasting (Artificer style) do not appear to calculate the correct number of prepared spells. Schedule 4 spellcasting was implemented in #494

To Reproduce

Steps to reproduce the behavior:

1. Create a custom class that uses Schedule 4 spellcasting
2. Create a character using the class.
3. View the number of prepared spells. Schedule 4 spellcasting should reflect spellcasting modifier + class level, rounded down. At 1st level, with a class set to Intelligence as its spellcasting ability and an intelligence of 12, the number of prepared spells should be 2; 1 for the INT mod and 1 for class, because half of 1 rounds down to 0, but you always prepare at least 1 spell
4. Error display as only 1 spell to prepare. If increasing custom class level to 6, with the same INT mod the number of prepared spells should be 4 (1 + 3). Instead it displays as 2.