Lowers named and glob node priority to fix lookup issue

Given two similar keys, one short and one with named parameter, lookup
was incorrectly picking up the named parameter version instead of the
specific one:

    tree = Radix::Tree(Symbol).new
    tree.add "/tag-edit/:id", :edit_tag
    tree.add "/tag-edit2", :alternate_edit_tag

    result = tree.find("/tag-edit2")
    result.found? # => false

The order of insertion (named before specific) was causing the
lookup mechanism to validate it before checking the other options.

With the changes present here, short or long keys will be affected
anymore by named or globbed keys present when sharing part of the
key.

Fixes kemalcr/kemal#293

spec/radix/node_spec.cr

@@ -46,18 +46,18 @@ module Radix
 
       it "returns zero for catch all (globbed) key" do
         node = Node(Nil).new("*filepath")
-        node.priority.should eq(0)
+        node.priority.should eq(-2)
 
         node = Node(Nil).new("/src/*filepath")
-        node.priority.should eq(0)
+        node.priority.should eq(-2)
       end
 
       it "returns one for keys with named parameters" do
         node = Node(Nil).new(":query")
-        node.priority.should eq(1)
+        node.priority.should eq(-1)
 
         node = Node(Nil).new("/search/:query")
-        node.priority.should eq(1)
+        node.priority.should eq(-1)
       end
 
       it "changes when key changes" do
@@ -68,10 +68,10 @@ module Radix
         node.priority.should eq(3)
 
         node.key = "*filepath"
-        node.priority.should eq(0)
+        node.priority.should eq(-2)
 
         node.key = ":query"
-        node.priority.should eq(1)
+        node.priority.should eq(-1)
       end
     end