WADS: Minor adjustments to some lq_tech textures

[kia100]

Description of Changes

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Looking through the lq_tech folder, I noticed a few of the textures could use some minor refinements, e.g. inconsistent palette change (plus_atek_jump1_fbr lacked a shade of color compared to the red palette swap) or poor shading (plus_0button3_fbr, plus_abutton3_fbr and spotlight_fbr were fleshed out with a bit of dithering).

EDIT: Due to the selection of very bright colors for spotlight_fbr, the difference isn't very apparent unless one looks closely. Still, dithering was added simply for the sake of consistancy.

Visual Sample

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Checklist

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• I have read the LibreQuake contribution guidelines
• I have thoroughly tested my changes to the best of my ability
• I confirm I have not contributed anything that would impact LibreQuake's licensing and usage
• This Pull Request fixes a critical issue that should be reviewed and merged as soon as possible

[lavenderdotpet]

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[kia100]

oooo

???

[lavenderdotpet]

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thanks for doing these dithered verions