Update Checks to Accomodate the Latest Steam Update

[gruenwaldlk]

Excerpts from the official changelog:

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[FOC] Added OR operator support for Required_Special_Structures field per community request. Details are below:

<Required_Special_Structures>
UNIT1 | UNIT2 UNIT3 | UNIT4
</Required_Special_Structures>

Note: This was implemented with the '|'(OR) behaving as you would expect as an OR relationship between operators. Everything else is as it worked before, being treated as an AND. In the above example, you would need to have already built UNIT1 OR UNIT2 AND UNIT3 OR UNIT4 to satisfy the requirement.
NOTE for the AI: It will probably only ever build the first thing in an OR situation. Therefore, with the above it would only try to build UNIT1 AND UNIT3 to satisfy the requirement.

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[FOC] Added support for a line which lets you specify the faction, so it's not just limited to the first three. (ie: <Story_Name>NewFaction, Story_Plots_Sandbox_56_NewFaction.xml </Story_Name>)

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[EAW/FOC] Corrected AI_Combat_Power for space invasions being ignored on special structures such as the Hypervelocity Gun and Ion Cannon which can damage units in space. This problem also seemed to ignore any secondary space structures. The AI would previously not send enough units to account for a defense with one of these structures. Additional details:

• Space special structures are now calculated as part of the SpaceTotalUnnormalized token. We modified the Garrison_Category to be a Space_Or_Garrison_Category. So something that can be garrisoned should also not be a special space structure.
• The XML tags <Garrison_Category> and <Space_Or_Garrison_Category> are actually the same. You can specify either one, but should only specify one, and they'll work the same for units and structures that can be garrisoned.
• For land-based space units and space special structures you can use the <Space_Or_Garrison_Category> as a secondary category mask for the AI to determine what to bring to counter. Since Structure is not one of the matching categories in PGAICommands.lua::Set_Contrast_Values(). If <Space_Or_Garrison_Category> is empty it will default to Capital for land-based space units and space special structures.

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[EAW/FOC] Added additional hidden build slots to tactical and galactic build bars that can be unlocked to increase the max number of units/buildings that can be displayed at one time.

[gruenwaldlk]

Moved to Milestone Steam Release

See issues #4 , #5 , #6 , #7