Add latex listings definition and vim syntax highlighting

contrib/ssm.sty

+% Make sure to include listings (https://www.ctan.org/pkg/listings)
+\lstdefinelanguage{SSM}{%
+	alsoletter={ABCDEFGHIJKLMNOPQRSTUVWXYZabcdefghijklmnopqrstuvwxyz1234567890_-},
+	morecomment=[l]{//},
+	morecomment=[l]{;},
+	morestring=[b]",
+	morekeywords={ldc,add,and,div,lsl,lsr,mod,mul,or,rol,ror,sub,xor,eq,ne,lt,gt,le,ge,ajs,bra,brf,brt,bsr,halt,jsr,lds,ldms,ldsa,lda,ldma,ldaa,ldc,ldl,ldml,ldla,link,nop,ret,sts,stms,sta,stma,stl,stml,swp,trap,unlink,ldh,ldmh,sth,stmh,ldr,ldrr,str,swpr,swprr,neg,not,annote,SP,MP,HP,RR,R0,R1,R2,R3,R4,R5,R6,R7}
+}

contrib/vim-ssm/ftdetect/ssm.vim

+au BufRead,BufNewFile *.ssm set filetype=ssm

contrib/vim-ssm/syntax/ssm.vim

+" Vim syntax file
+" " Language: SSM
+" " Maintainer: Mart
+" " Version: 1.0
+" " Latest Revision: 2020-05-01
+
+if exists("b:current_syntax")
+	finish
+endif
+
+syn keyword ssmKeyword ldc add and div lsl lsr mod mul or rol ror sub xor eq ne lt gt le ge ajs bra brf brt bsr halt jsr lds ldms ldsa lda ldma ldaa ldc ldl ldml ldla link nop ret sts stms sta stma stl stml swp trap unlink ldh ldmh sth stmh ldr ldrr str swpr swprr neg not annote
+syn keyword ssmKeyword LDC ADD AND DIV LSL LSR MOD MUL OR ROL ROR SUB XOR EQ NE LT GT LE GE AJS BRA BRF BRT BSR HALT JSR LDS LDMS LDSA LDA LDMA LDAA LDC LDL LDML LDLA LINK NOP RET STS STMS STA STMA STL STML SWP TRAP UNLINK LDH LDMH STH STMH LDR LDRR STR SWPR SWPRR NEG NOT ANNOTE
+syn keyword ssmRegister SP MP HP RR R0 R1 R2 R3 R4 R5 R6 R7
+
+syn match sssNumbers '[-]\(0x\x\+\|\d\+\)'
+syn match ssmString '"\(\\.\?"\|[^"]\)*"'
+syn match ssmLabel '[a-zA-Z0-9_-]\+:'
+
+syn region ssmComment start="\(//\|;\)" end="$" contains=@Spell oneline display
+syn region ssmString start=+"+ skip=+\\\\\|\\"+ end=+"+ oneline contains=@Spell
+
+hi def link ssmLabel Label
+hi def link ssmComment Comment
+hi def link ssmString String
+hi def link ssmNumber Number
+hi def link ssmKeyword Keyword
+hi def link ssmRegister Keyword