Update APL lexer to cope with current Dyalog APL

* Names can start with underscore
* Missing APL primitive ops: ⍥@⌺⌶⍢
* Missing APL primitive funcs: ⊆⍸

Author: xpqz

Diff for: lexers/a/apl.go

@@ -26,10 +26,10 @@ func aplRules() Rules {
 			{`[⋄◇()]`, Punctuation, nil},
 			{`[\[\];]`, LiteralStringRegex, nil},
 			{`⎕[A-Za-zΔ∆⍙][A-Za-zΔ∆⍙_¯0-9]*`, NameFunction, nil},
-			{`[A-Za-zΔ∆⍙][A-Za-zΔ∆⍙_¯0-9]*`, NameVariable, nil},
+			{`[A-Za-zΔ∆⍙_][A-Za-zΔ∆⍙_¯0-9]*`, NameVariable, nil},
 			{`¯?(0[Xx][0-9A-Fa-f]+|[0-9]*\.?[0-9]+([Ee][+¯]?[0-9]+)?|¯|∞)([Jj]¯?(0[Xx][0-9A-Fa-f]+|[0-9]*\.?[0-9]+([Ee][+¯]?[0-9]+)?|¯|∞))?`, LiteralNumber, nil},
-			{`[\.\\/⌿⍀¨⍣⍨⍠⍤∘]`, NameAttribute, nil},
-			{`[+\-×÷⌈⌊∣|⍳?*⍟○!⌹<≤=>≥≠≡≢∊⍷∪∩~∨∧⍱⍲⍴,⍪⌽⊖⍉↑↓⊂⊃⌷⍋⍒⊤⊥⍕⍎⊣⊢⍁⍂≈⌸⍯↗]`, Operator, nil},
+			{`[\.\\/⌿⍀¨⍣⍨⍠⍤∘⍥@⌺⌶⍢]`, NameAttribute, nil},
+			{`[+\-×÷⌈⌊∣|⍳?*⍟○!⌹<≤=>≥≠≡≢∊⍷∪∩~∨∧⍱⍲⍴,⍪⌽⊖⍉↑↓⊂⊃⌷⍋⍒⊤⊥⍕⍎⊣⊢⍁⍂≈⌸⍯↗⊆⍸]`, Operator, nil},
 			{`⍬`, NameConstant, nil},
 			{`[⎕⍞]`, NameVariableGlobal, nil},
 			{`[←→]`, KeywordDeclaration, nil},