Non-blacksmithy changes from blacksmithy PR.

[MistakeNot4892]

• Merges shake() and shake_animation() at /atom level.
• Privates filter_data and adds a has_filter() proc.
• Adds a delta param to get_thermal_mass_coefficient() to allow for faster cooling than heating.
• Generalizes HE pipe glow effects to /obj.
• Adds a silent spark subtype.
• Adds a bar recipe to soft materials.
• Adds an iron knife subtype and replaces knives on Shaded Hills with it.
• Adds debug strings to admin examining hot atoms.
• Skips structure hitsound if silent is TRUE.
• Adds an iron forging hammer.
• Renames the 'meat hook' item to 'hook'.
• Adds mapped iron and copper bar subtypes.

[MistakeNot4892]

Will atomise this if requested, but I just tried and got really bored.