Additional Compiler Warnings

[zfergus]

Add additional compiler warnings and resolve them to be warning-free.

[codecov]

Codecov Report

Merging #73 (4268d07) into main (5370866) will increase coverage by 0.00%.
The diff coverage is 97.95%.

@@           Coverage Diff           @@
##             main      #73   +/-   ##
=======================================
  Coverage   95.11%   95.12%           
=======================================
  Files          87       87           
  Lines        7251     7256    +5     
=======================================
+ Hits         6897     6902    +5     
  Misses        354      354           

Files	Coverage Δ
src/ipc/broad_phase/aabb.cpp	100.00% <100.00%> (ø)
src/ipc/broad_phase/hash_grid.cpp	100.00% <100.00%> (ø)
src/ipc/broad_phase/hash_grid.hpp	100.00% <100.00%> (ø)
src/ipc/broad_phase/sweep_and_tiniest_queue.cpp	66.66% <100.00%> (ø)
src/ipc/broad_phase/sweep_and_tiniest_queue.hpp	100.00% <ø> (ø)
src/ipc/broad_phase/voxel_size_heuristic.cpp	95.58% <100.00%> (ø)
src/ipc/candidates/candidates.cpp	91.19% <100.00%> (ø)
src/ipc/candidates/edge_edge.cpp	82.00% <100.00%> (ø)
src/ipc/candidates/edge_face.cpp	100.00% <100.00%> (ø)
src/ipc/candidates/edge_vertex.cpp	85.10% <100.00%> (ø)
... and 20 more