Fix memory leak

[jgostick]

The project object was making a copy of itself if a slice was used in the index. Switching back to inheriting from list.

[codecov]

Codecov Report

Merging #2809 (9357da5) into dev (8f56cb0) will increase coverage by 0.0%.
Report is 16 commits behind head on dev.
The diff coverage is 83.3%.

Additional details and impacted files

@@          Coverage Diff          @@
##             dev   #2809   +/-   ##
=====================================
  Coverage   90.2%   90.3%           
=====================================
  Files        146     147    +1     
  Lines       8572    8562   -10     
=====================================
- Hits        7740    7732    -8     
+ Misses       832     830    -2