[#1824] createTransformerFactory useCache new param

[laurentschoelens]

Fixes #1824

Optimize createTransformerHandler / createTransformer

With actual 4.0.6 :

• With Saxon : 5 in 64.100840667 seconds
• Without : 5 in 0.632727292 seconds

With patched 4.0.7-SNAPSHOT :

• With Saxon : 5 in 0.731846333 seconds
• Without : 5 in 0.497841 seconds

[mkarg]

I wonder why nobody reviewed this several weeks old PR?

[lukasj]

let's go with this one; just amend the commit so @mkarg is mentioned as author/co-author since the main idea is from him

[laurentschoelens]

let's go with this one; just amend the commit so @mkarg is mentioned as author/co-author since the main idea is from him

I'll amend my commit message to mention mkarg as co-author as suggested

[laurentschoelens]

@lukasj : rebase done with new commit message
be67dab