Add some Xilinx BGA packages.

Created by: ObKo

Used in new Spartan-7 FPGA family.

• CP(G)(A)196: 14x14 pins, 8x8mm size, 0.5mm pitch - https://www.xilinx.com/support/documentation/package_specs/pk400_CPG196.pdf
• FT(G)(B)196: 14x14 pins, 15x15mm size, 1.0mm pitch - https://www.xilinx.com/support/documentation/user_guides/ug475_7Series_Pkg_Pinout.pdf (can't find separate pdf)
• CS(G)(A)225: 15x15 pins, 13x13mm size, 0.8mm pitch - https://www.xilinx.com/support/documentation/package_specs/pk380_CS_G_225.pdf
• CS(G)(A)324: 18x18 pins, 15x15mm size, 0.8mm pitch - https://www.xilinx.com/support/documentation/package_specs/pk381_CSG324.pdf (already in KiCAD library)
• FG(G)(A)484: 22x22 pins, 23x23mm size, 1.0mm pitch - https://www.xilinx.com/support/documentation/package_specs/fg484.pdf (already in KiCAD library)
• FG(G)(A)676: 26x26 pins, 27x27mm size, 1.0mm pitch - https://www.xilinx.com/support/documentation/package_specs/fg676.pdf (already in KiCAD library)