Add 'delim' to vecrow(..)

Fixed #24.

physica-manual.typ

@@ -149,7 +149,7 @@ All symbols need to be used in *math mode* `$...$`.
 #v(1em)
 
 #table(
-  columns: (5fr, 2fr, 6fr, 5fr),
+  columns: (5fr, 2fr, auto, 5fr),
   align: left,
   stroke: none,
   [*Symbol*], [*Abbr.*], [*Example*], [*Notes*],
@@ -163,7 +163,7 @@ All symbols need to be used in *math mode* `$...$`.
   [],
   [
     `vecrow(alpha, b)` \ #sym.arrow $vecrow(alpha, b)$ \
-    `vecrow(sum_0^n a_i, b)` \ #sym.arrow $vecrow(sum_0^n a_i,b)$ \
+    `vecrow(sum_0^n i, b, delim:"[")` \ #sym.arrow $vecrow(sum_0^n i,b,delim:"[")$ \
   ],
   [row vector],
 
@@ -205,7 +205,7 @@ All symbols need to be used in *math mode* `$...$`.
   [`laplacian`],
   [],
   [`diaer(u) = c^2 laplacian u` \ #sym.arrow $diaer(u) = c^2 laplacian u$],
-  [Laplacian, different from #builtin(`laplace`) $laplace$],
+  [Laplacian,\ not #builtin(`laplace`) $laplace$],
 
   [`dotproduct`],
   [`dprod`],

physica.typ

@@ -177,7 +177,24 @@
 
 // == Vector notations
 
-#let vecrow(..content) = $lr(( #content.pos().join([,]) ))$
+#let vecrow(..sink) = {
+  let (args, kwargs) = (sink.pos(), sink.named())  // array, dictionary
+  let delim = kwargs.at("delim", default:"(")
+  let rdelim = if delim == "(" {
+    ")"
+  } else if delim == "[" {
+    "]"
+  } else if delim == "{" {
+    "}"
+  } else if delim == "|" {
+    "|"
+  } else if delim == "||" {
+    "||"
+  } else { delim }
+  // not math.mat(), because the look would be off: the content
+  // appear smaller than the sorrounding delimiter pair.
+  $lr(#delim #args.join([,]) #rdelim)$
+}
 
 // Prefer using super-T-as-transpose() found below.
 //