Add a dispatch on dagger for Eye to keep sparsity (#153)

Author: david-pl

.gitignore

@@ -1,2 +1,3 @@
 /docs/build/
 Manifest.toml
+.vscode

src/operators_sparse.jl

@@ -109,7 +109,7 @@ mul!(result::Bra{B2},b::Bra{B1},M::SparseOpPureType{B1,B2},alpha,beta) where {B1
 -(op1::EyeOpType{BL,BR},op2::SparseOpType{BL,BR}) where {BL,BR} = sparse(op1) - op2
 +(op1::SparseOpType{BL,BR},op2::EyeOpType{BL,BR}) where {BL,BR} = sparse(op2) + op1
 -(op2::SparseOpType{BL,BR},op1::EyeOpType{BL,BR}) where {BL,BR} = op2 - sparse(op1)
-+(op1::EyeOpType{BL,BR},op2::EyeOpType{BL,BR}) where {BL,BR} = sparse(op1) + sparse(op1)
++(op1::EyeOpType{BL,BR},op2::EyeOpType{BL,BR}) where {BL,BR} = sparse(op1) + sparse(op2)
 -(op2::EyeOpType{BL,BR},op1::EyeOpType{BL,BR}) where {BL,BR} = sparse(op2) - sparse(op1)
 -(op::EyeOpType) = -sparse(op)
 *(op::EyeOpType,a::T) where {T<:Number} = a*sparse(op)
@@ -118,3 +118,4 @@ mul!(result::Bra{B2},b::Bra{B1},M::SparseOpPureType{B1,B2},alpha,beta) where {B1
 tensor(a::EyeOpType, b::SparseOpType) = tensor(sparse(a),b)
 tensor(a::SparseOpType, b::EyeOpType) = tensor(a,sparse(b))
 tensor(a::EyeOpType, b::EyeOpType) = tensor(sparse(a),sparse(b))
+dagger(a::EyeOpType) = dagger(sparse(a))