* Pay X abilities - fixed that it spends all available mana pool instead only needed;
* Pay X abilities - added support of interactions with other X effects like Rosheen Meanderer's mana usage for "pay X to prevent";
* Rosheen Meanderer - fixed that it can't use mana for "you may pay X" like Flameblast Dragon's effect (#5206);
* Devs: added support to use VariableManaCost to pay X in code (without generic's workaround, use ManaUtil.createManaCost to generate cost to pay);
