Promotion black carpace

[OH296]

• allows scouts to gain a black carpace during promotion (gives minor stat boost);
• refactor of promotion scripts
• "promotion" of squads
• full promotion ui refactor

[GalacticChimp]

tried to promote a Salamander Scout into a Devastator into an empty company, but got a crash:

___________________________________________
############################################################################################
ERROR in
action number 1
of Mouse Event for Glob Left Button
for object obj_popup:

Variable obj_popup.comp(100763, -2147483648) not set before reading it.
 at gml_Object_obj_popup_Mouse_50 (line 736) -             if (obj_ini.name[target_[comp][i]]=="" and obj_ini.name[target_[comp][i]+1]=="") {
############################################################################################
gml_Object_obj_popup_Mouse_50 (line 736)

same for Ultrasmurf Scout -> Devastator -> 9th (already had marines in it)

[OH296]

should be all sorted still working on making squads promote (so if you promotea all of a scout to tactiacals it just makes the squad a tact squad) but probably not a bad thing to just have that as a dedicated pr /

[OH296]

okay made some final adjustments in line with comments and made squad promotion fully viable

[OH296]

addressed most recent review points as best as i can, and as an added bonus added the requested specialist check method. Will look into porting more into company struct and improving gene_seed_mutation data but that's put of scope of this pr.