Doc: Fix various inconsistencies

This fixes multiple areas of the documentation:
- COPY for its past compatibility section.
- SET ROLE mentioning INHERITS instead of INHERIT
- PREPARE referring to stmt_name, that is not present.
- Extension documentation about format name with upgrade scripts.

Backpatch down to 9.4 for the relevant parts.

Author: Alexander Lakhin
Discussion: https://postgr.es/m/bf95233a-9943-b341-e2ff-a860c28af481@gmail.com
Backpatch-through: 9.4

doc/src/sgml/extend.sgml

@@ -856,7 +856,7 @@ SELECT pg_catalog.pg_extension_config_dump('my_config', 'WHERE NOT standard_entr
      dynamically from one version to the next, you should provide
      <firstterm>update scripts</firstterm> that make the necessary changes to go from
      one version to the next.  Update scripts have names following the pattern
-     <literal><replaceable>extension</replaceable>--<replaceable>oldversion</replaceable>--<replaceable>newversion</replaceable>.sql</literal>
+     <literal><replaceable>extension</replaceable>--<replaceable>old_version</replaceable>--<replaceable>target_version</replaceable>.sql</literal>
      (for example, <literal>foo--1.0--1.1.sql</literal> contains the commands to modify
      version <literal>1.0</literal> of extension <literal>foo</literal> into version
      <literal>1.1</literal>).

doc/src/sgml/ref/copy.sgml

@@ -1002,11 +1002,11 @@ COPY <replaceable class="parameter">table_name</replaceable> [ ( <replaceable cl
     [ [ WITH ]
           [ BINARY ]
           [ OIDS ]
-          [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter</replaceable>' ]
+          [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter_character</replaceable>' ]
           [ NULL [ AS ] '<replaceable class="parameter">null string</replaceable>' ]
           [ CSV [ HEADER ]
-                [ QUOTE [ AS ] '<replaceable class="parameter">quote</replaceable>' ]
+                [ QUOTE [ AS ] '<replaceable class="parameter">quote_character</replaceable>' ]
-                [ ESCAPE [ AS ] '<replaceable class="parameter">escape</replaceable>' ]
+                [ ESCAPE [ AS ] '<replaceable class="parameter">escape_character</replaceable>' ]
                 [ FORCE NOT NULL <replaceable class="parameter">column_name</replaceable> [, ...] ] ] ]
 
 COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable class="parameter">column_name</replaceable> [, ...] ) ] | ( <replaceable class="parameter">query</replaceable> ) }
@@ -1014,11 +1014,11 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
     [ [ WITH ]
           [ BINARY ]
           [ OIDS ]
-          [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter</replaceable>' ]
+          [ DELIMITER [ AS ] '<replaceable class="parameter">delimiter_character</replaceable>' ]
           [ NULL [ AS ] '<replaceable class="parameter">null string</replaceable>' ]
           [ CSV [ HEADER ]
-                [ QUOTE [ AS ] '<replaceable class="parameter">quote</replaceable>' ]
+                [ QUOTE [ AS ] '<replaceable class="parameter">quote_character</replaceable>' ]
-                [ ESCAPE [ AS ] '<replaceable class="parameter">escape</replaceable>' ]
+                [ ESCAPE [ AS ] '<replaceable class="parameter">escape_character</replaceable>' ]
                 [ FORCE QUOTE { <replaceable class="parameter">column_name</replaceable> [, ...] | * } ] ] ]
 </synopsis>
 
@@ -1034,13 +1034,13 @@ COPY { <replaceable class="parameter">table_name</replaceable> [ ( <replaceable
 <synopsis>
 COPY [ BINARY ] <replaceable class="parameter">table_name</replaceable> [ WITH OIDS ]
     FROM { '<replaceable class="parameter">filename</replaceable>' | STDIN }
-    [ [USING] DELIMITERS '<replaceable class="parameter">delimiter</replaceable>' ]
+    [ [USING] DELIMITERS '<replaceable class="parameter">delimiter_character</replaceable>' ]
-    [ WITH NULL AS '<replaceable class="parameter">null string</replaceable>' ]
+    [ WITH NULL AS '<replaceable class="parameter">null_string</replaceable>' ]
 
 COPY [ BINARY ] <replaceable class="parameter">table_name</replaceable> [ WITH OIDS ]
     TO { '<replaceable class="parameter">filename</replaceable>' | STDOUT }
-    [ [USING] DELIMITERS '<replaceable class="parameter">delimiter</replaceable>' ]
+    [ [USING] DELIMITERS '<replaceable class="parameter">delimiter_character</replaceable>' ]
-    [ WITH NULL AS '<replaceable class="parameter">null string</replaceable>' ]
+    [ WITH NULL AS '<replaceable class="parameter">null_string</replaceable>' ]
 </synopsis></para>
  </refsect1>
 </refentry>

doc/src/sgml/ref/set_role.sgml

@@ -64,7 +64,7 @@ RESET ROLE
 
   <para>
    Using this command, it is possible to either add privileges or restrict
-   one's privileges.  If the session user role has the <literal>INHERITS</literal>
+   one's privileges.  If the session user role has the <literal>INHERIT</literal>
    attribute, then it automatically has all the privileges of every role that
    it could <command>SET ROLE</command> to; in this case <command>SET ROLE</command>
    effectively drops all the privileges assigned directly to the session user