Make lu! reuse working buffers

[SobhanMP]

had to close #104 due to ... issues with git.

[SobhanMP]

@ViralBShah is there any reason to not merge this and the qsymbolic patch atm? (after CI of-course) both are non-breaking

[ViralBShah]

Yes, let's merge. I'll let you go about the merging to minimize conflicts if there are.

[SobhanMP]

i think this should go first but i think there are a bunch of conflicts..i'll fix them after you merged this one.

[SobhanMP]

also if you meant that i should do the merges myself, i don't have write access

[codecov-commenter]

Codecov Report

Merging #179 (672a6bd) into main (7745517) will increase coverage by 2.25%.
The diff coverage is 81.81%.

@@            Coverage Diff             @@
##             main     #179      +/-   ##
==========================================
+ Coverage   34.25%   36.50%   +2.25%     
==========================================
  Files          25       25              
  Lines       21127    21899     +772     
==========================================
+ Hits         7237     7995     +758     
- Misses      13890    13904      +14     

Impacted Files	Coverage Δ
src/solvers/umfpack.jl	86.72% <81.81%> (+1.35%)	⬆️
src/sparsevector.jl	94.58% <0.00%> (+0.41%)	⬆️
src/sparsematrix.jl	95.76% <0.00%> (+0.47%)	⬆️

📣 Codecov can now indicate which changes are the most critical in Pull Requests. Learn more

[ViralBShah]

I thought I had given you write access - Seems like I still haven't understood the latest iteration of github permissioning. Anyways, added you now - you should be able to merge.