Merge branch 'diagonal' into 'main'

Replace eigen sparse matrices with the diagonal optimization

See merge request naaice/tug!39

CITATION.cff

@@ -1,30 +1,25 @@
 cff-version: 1.2.0
-title: tug: Transport on Uniform Grids
+title: TUG
 message: >-
   If you use this software, please cite it using the
   metadata from this file.
 type: software
 authors:
-- given-names: Marco
-    family-names: De Lucia
-    email: delucia@gfz.de
-    orcid: 'https://orcid.org/0009-0000-3058-8472'
-- given-names: Max
+  - given-names: Max
     family-names: Lübke
-    email: max.luebke@uni-potsdam.de
+    email: mluebke@uni-potsdam.de
     orcid: 'https://orcid.org/0009-0008-9773-3038'
-- given-names: Bettina
-    family-names: Schnor
-    email: schnor@cs.uni-potsdam.de
-    orcid: 'https://orcid.org/0000-0001-7369-8057'
-- given-names: Hannes
+  - given-names: Philipp
+    family-names: Ungrund
+    email: ungrund@uni-potsdam.de
+  - given-names: Hannes
     family-names: Signer
     email: signer@uni-potsdam.de
     orcid: 'https://orcid.org/0009-0000-3058-8472'
-- given-names: Philipp
-    family-names: Ungrund
-    email: ungrund@uni-potsdam.de
-    orcid: 'https://orcid.org/0009-0007-0182-4051'
+  - given-names: Marco
+    family-names: De Lucia
+    email: delucia@gfz.de
+    orcid: 'https://orcid.org/0009-0000-3058-8472'
 repository-code: 'https://github.com/POET-Simulator/tug'
 abstract: >-
   tug implements different numerical approaches for