Add c:vector as c:set alternative

The term "set" is all wrong---it is actally intended to be a vector, and can
absolutely have duplicate elements (and often does).

* src/current/calc.xsd (vector): Add, recommending in place of `set'.
* src/current/compiler/js-calc.xsl (compile-calc)[c:set|c:vector]:
    Add `c:vector' and provide deprecation notice for `c:set'.
* src/current/include/calc-display.xsl (c:set|c:vector): Likewise.

src/current/calc.xsd

@@ -580,7 +580,22 @@
     <xs:element name="set" substitutionGroup="operator">
       <xs:annotation>
         <xs:documentation xml:lang="en">
-          Creates a set out of its siblings
+          Creates a set out of its siblings (deprecated in favor of
+          c:vector)
+        </xs:documentation>
+      </xs:annotation>
+
+      <xs:complexType>
+        <xs:complexContent>
+          <xs:extension base="operatorBaseType" />
+        </xs:complexContent>
+      </xs:complexType>
+    </xs:element>
+
+    <xs:element name="vector" substitutionGroup="operator">
+      <xs:annotation>
+        <xs:documentation xml:lang="en">
+          Creates a vector out of its siblings
         </xs:documentation>
       </xs:annotation>
 

src/current/compiler/js-calc.xsl

@@ -1009,7 +1009,16 @@
 </template>
 
 
-<template match="c:set" mode="compile-calc">
+<!--
+  TODO: Remove c:set in the future.
+-->
+<template match="c:set" mode="compile-calc" priority="9">
+  <message select="'warning: c:set is deprecated; use c:vector instead'" />
+  <next-match />
+</template>
+
+
+<template match="c:set|c:vector" mode="compile-calc" priority="5">
   <text>[</text>
     <for-each select="./c:*">
       <if test="position() > 1">

src/current/include/calc-display.xsl

@@ -671,10 +671,9 @@
 
 
 <!--
-  TODO: Technically this is incorrect; sets cannot have duplicate values. This
-  would be best styled as a vector/matrix/etc.
+  Style vectors
 -->
-<xsl:template match="c:set" priority="1">
+<xsl:template match="c:set|c:vector" priority="1">
   <xsl:text>\left[</xsl:text>
     <xsl:for-each select="./c:*">
       <xsl:if test="position() > 1">
@@ -686,11 +685,16 @@
   <xsl:text>\right]^T</xsl:text>
 </xsl:template>
 
-<!-- style subsets as matrices (easier to read) -->
-<xsl:template match="c:set[ ./c:set ]" priority="5">
+
+<!--
+  Style vector of vector as matrix
+-->
+<xsl:template priority="5"
+              match="c:set[ c:set ]
+                     |c:vector[ c:vector ]">
   <xsl:text>\left[\begin{array}\\</xsl:text>
 
-  <xsl:for-each select="./c:set">
+  <xsl:for-each select="c:set|c:vector">
     <xsl:if test="position() > 1">
       <xsl:text>\\</xsl:text>
     </xsl:if>