rust: Add several fixes

pyproject.toml

@@ -131,7 +131,7 @@ asv = ["asv-run", "asv-publish", "asv-preview"]
 bump-version = { "shell" = "python crates/bump-versions.py $(git describe --tags)" }
 compile = "pip install -e crates/eko/"
 rdocs.cmd = "cargo doc --workspace --no-deps"
-rdocs.env = { RUSTDOCFLAGS = "--html-in-header crates/katex-header.html" }
+rdocs.env = { RUSTDOCFLAGS = "--html-in-header crates/doc-header.html" }
 rdocs-view = "xdg-open target/doc/ekors/index.html"
 rdocs-clean = "rm -rf target/doc/"
 rtest = "cargo test --workspace"

src/eko/evolution_operator/operator_matrix_element.py.patch

@@ -1,5 +1,5 @@
 diff --git a/src/eko/evolution_operator/operator_matrix_element.py b/src/eko/evolution_operator/operator_matrix_element.py
-index 202fd18d..3bdabab7 100644
+index 202fd18d..5b0716cf 100644
 --- a/src/eko/evolution_operator/operator_matrix_element.py
 +++ b/src/eko/evolution_operator/operator_matrix_element.py
 @@ -1,11 +1,13 @@
@@ -222,7 +222,7 @@ index 202fd18d..3bdabab7 100644
 +                cfg.mode1 = label[1]
 +                # construct the low level object
 +                func = LowLevelCallable(
-+                    ekors.lib.rust_quad_ker_ome, ekors.ffi.addressof(cfg)
++                    ekors.lib.rust_quad_ker_qcd, ekors.ffi.addressof(cfg)
 +                )
 +                res = integrate.quad(
 +                    func,

src/eko/evolution_operator/quad_ker.py

@@ -273,7 +273,7 @@ def cb_quad_ker_ome(
         A = sv.exponentiated.gamma_variation(A, order, nf, Lsv)
 
     # TODO recover InversionMethod
-    backward_method = "exact"
+    backward_method = ""
 
     # build the expansion in alpha_s depending on the strategy
     ker = build_ome(A, order, as1, backward_method)