Added generic plugin mechanism to define custom match placement styles.

Animate now allows users to define their own match placement patterns.

This is defined as a SKILL function that is imported from the Animate custom match styles file. The file is pointed to from the env var PULSIC_ANIMATE_CUSTOM_MATCH_STYLES_PATH which contains an xml file that has a name for the pattern and a SKILL callback function defined.

If a solution is returned to Animate from this defined callback, when selected, Animate will use the placement that is defined, provided that it passes the validity checks and the instances are as expected. The solution is row-based. This requires Virtuoso 25.1 ISR4 or later.