A minor tweak to the syringe's description.

Syringes, not just for needle junkies any more!
Renaming cough syrup.

We have 'cola' and 'candy bars' and 'potato chips' so why are we using a
specific brand name here? The only place we consistently do that is with
firearms, so this is for consistency and it makes it easier for
non-American players to immediately get what this item is supposed to
be.
Aspirin description tweak.

None of this statement is true in real life or in the game.
Merge pull request #6122 from Rivet-the-Zombie/syringe-description-tweak

Some medical item description tweaks.