Make conflict resolution strategies configurable

[snikolayev]

Currently, conflict resolution strategy in NRules is fixed. Rules with higher priorities are fired first. Rules with the same priority are fired in a FIFO order.
Need ability to control conflict resolution at a more granular level.

[linanqiu]

Possible strategies;

• Alphabetical (as default)
• Analyze expressions and find dependency in types (e.g. if Rule A forward chains Type1 and Rule B consumes Type1, and RuleA's priority is the same as RuleB's, then always prefer RuleA)

This allows users to define fewer explicit rule groups.

[snikolayev]

FYI, if priorities are the same, the default firing order is not alphabetical, it preserves activation order.

[linanqiu]

My bad -- that should be the default yes.