Fix crash on legend icon with offset generation (#4790)
Don't allow in-source builds, they are a source of confusion
use lib64 instead of lib for installing on select linux systems (#4789)
Merge branch 'branch-6-4'

Conflicts:
	CMakeLists.txt
	maplegend.c
Fix csharp build issues when doing out-of-source builds
Merge branch 'branch-6-4'