the single argument operation Category is not an attribute anymore

Author: mohamed-barakat

PackageInfo.g

@@ -11,7 +11,7 @@ SetPackageInfo( rec(
 PackageName := "Algebroids",
 Subtitle := "Algebroids and bialgebroids as preadditive categories generated by enhanced quivers",
 Version := Maximum( [
-                   "2020.10-10", ## Mohamed's version
+                   "2020.10-11", ## Mohamed's version
                    ## this line prevents merge conflicts
                    "2020.09-08", ## Kamal's version
                    ## this line prevents merge conflicts

gap/FpCategories.gd

@@ -275,8 +275,9 @@ DeclareGlobalFunction( "ADD_FUNCTIONS_FOR_HOM_STRUCTURE_OF_FP_CATEGORY" );
 
 DeclareGlobalFunction( "ADD_FUNCTIONS_FOR_RANDOM_METHODS_OF_FP_CATEGORY" );
 
-DeclareAttribute( "Category",
-        IsQuiverAlgebra );
+# do not turn this into an attribute:
+DeclareOperation( "Category",
+        [ IsQuiverAlgebra ] );
 
 DeclareOperation( "Category",
         [ IsPathAlgebra, IsList ] );
@@ -287,8 +288,8 @@ DeclareOperation( "Category",
 #! @Arguments q
 #! @Returns a ∩ category
 #! @Group FpCategory
-DeclareAttribute( "Category",
-        IsQuiver );
+DeclareOperation( "Category",
+        [ IsQuiver ] );
 
 #! @Arguments q, L
 #! @Group FpCategory

gap/FpCategories.gi

@@ -429,7 +429,7 @@ InstallMethod( Category,
 end );
 
 ##
-InstallMethod( Category,
+InstallMethodWithCache( Category,
         "for a QPA quiver",
         [ IsQuiver ],