SillyTavern-Mathcros v1.2.0

• PR Title: Compatibility with CC and QOL changes
• Merged by: @leandrojofre

Changes

• Docs - Update docs
• Update - Allow to negate variables

A - at the start of a variable name will negate the final numeric value of the variable.

• Feat - Add compatibility with Chat Completion
• Docs - Update JS docs
• Update README.md
• Update README.md
• Update manifest.json