Re-use loaded rules

[slotties]

Rules loaded by JLanguageTool.activateDefaultPatternRules() and JLanguageTool.activateDefaultFalseFriendRules() should be cached outside the JLanguageTool and be provided to it on creation.

The goal of this issue is to increase the speed and reduce the memory consumption of creating new JLanguageTools.

One choice is to move both methods to Language. The caller is able to cache the different variants of a Language then, e.g. "english with enabled pattern rules" and "english without pattern rules".

Various things must be taken care of:

• where are user rules (JLanguageTool.addRule, JLanguageTool.disableRule, etc.) stored?
• where are ignored words stored (JLanguageTool.addIgnoreWords adds them on the rule)?
• any other things?

Constraints:

• no changes on the XML structure
• all the rule-loading and rule-management methods from JLanguageTool must still work. The new mechanism just enables more possibilities to cache for an API-user.
• no changes on existing testing code (backward-compatibility)

[danielnaber]

Closing, this is basically implemented with the new Language.getPatternRules() now.