Fix PriorityReplace

[jcoupey]

Issue

Fixes #1162

Tasks

• Add checks for pending deliveries for PriorityReplace
• If start route replacement split has a pending delivery problem, try finding a smaller start route without splitting problem
• If end route replacement split has a pending delivery problem, try finding a smaller end route without splitting problem
• Account for number of tasks after applying to discriminate between start or end replacement if both are valid
• Update CHANGELOG.md
• review