Implement max number for column labels

Description

This MR adds the possibility to limit the maximum number of ticks when customcolumn is used. The problem is if customcolumn contains a lot of rows, a many ticks and many labels are drawn. This slows the application extremely down. Now there is a possibility to select the number of ticks drawn even for custom columns so the user can limit the number if there are too many and laplot is slow

Conformity

• Changelog entry
• Unit tests
• Update INSTALL
• Downport
• Fixes: #823 (closed)

When external dependencies are removed

• Reporting to ...