Allow setting a different alignment for each section

[karas84]

Currently, splat allows setting a subalign value for each YAML segment (e.g. "main"). This sets the subalign value in the linkerscript for all the sections in the segment (.text, .data, etc.).

This is a problem for those games that have different align values for different sections. For example, PS2 games have functions in .text with subalign 8, but symbols in .data might need a different subalign, e.g., 2.

Allowing per-subsegment subalign, such as:

- { start: 0x00112233, type: .data, name: path/to/file, subalign: 2 }

would allow splat to generate a linkerscript that would work without extra processing.