Fixes misc grammar issues

- Fixes a lot of occurences of "the the" in game messages for mech fabricators and eating. Makes eating message colour consistent with drinking message colour. They were different shades of blue because only one used the notice span class. =0

- Gives a lot of mineral sheets their missing singular_name which was causing an extra space in their examine message. Also adds a check so if a new mineral is added without a singular_name the stack examine() proc won't bother looking for the undefined var.

- Due to there being no are/is macro in BYOND to my knowledge, added different examine messages based on whether or not the amount in a stack exceeds 1. If it doesn't, the description uses is. e.g. There is 1 metal sheet in the stack.

- Removes "They have been dubbed Metal Sheets." from the metal sheets description because why.

- Replaces manually written nouns associated with mech fabricators with [src] for simplicity's sake. I don't know why you'd rename a mech fabricator, but if you do it'll be referred to by its new name in game messages.

- Renames tool-belt toolbelt because it's grammatically correct and that has bugged me forever.

- Fixes #2710. The stamping out smokes message will no longer read the lit the lit.