Make project tree sort order case insensitive

[tanius]

Currently, the alphanumeric sort order of project items on one level of the project tree is case-sensitive, like this:

• 123 project
• A project
• Z project
• a project
• z project

As one cannot necessarily remember if one named a project with s lowercase or uppercase letter at its start, that's a bit cumbersome / confusing. Case-insensitive seems more intuitive:

• 123 project
• A project
• a project
• Z project
• z project

[jansorg]

Fixed for next update.