ENH: improve handling of mismatched brackets, forgotten ';' (issue #762)

- flags the following type of problems:

  * mismatches:

        keyword  mismatch ( set of { brackets ) in the } entry;

  * underflow (too many closing brackets:

        keyword  too many ( set of ) brackets ) in ) entry;

- a missing semi-colon

        dict
        {
           keyword  entry with missing semi-colon
        }

  will be flagged as 'underflow', since it parses through the '}' but
  did not open with it.

Max monitoring depth is 60 levels of nesting, to avoid incurring any
memory allocation.

applications/test/dictionary/testPrimitiveEntry

@@ -0,0 +1,49 @@
+/*--------------------------------*- C++ -*----------------------------------*\
+| =========                 |                                                 |
+| \\      /  F ield         | OpenFOAM: The Open Source CFD Toolbox           |
+|  \\    /   O peration     | Version:  plus                                  |
+|   \\  /    A nd           | Web:      www.OpenFOAM.com                      |
+|    \\/     M anipulation  |                                                 |
+\*---------------------------------------------------------------------------*/
+FoamFile
+{
+    version     2.0;
+    format      ascii;
+    class       dictionary;
+    object      testDict;
+}
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //
+
+// Test parsing of primitive entry
+// Can pass through foamDictionary -expand for test
+
+dict1
+{
+    entry1  no brackets;
+
+    entry2  balanced ( set of { brackets } in the ) entry;
+
+    entry3a mismatch ( set of { brackets ) in the } entry;
+
+    entry3b mismatch ( set of { brackets } in the } entry;
+
+    // Runs on
+    // entry3c too many ( set of ) brackets ) in ) entry;
+
+    //entry4  missing closing ( set of { brackets } in entry;
+}
+
+
+dict2
+{
+    entry1  no brackets;
+    entry2  no brackets but missing semi-colon
+}
+
+dict3
+{
+    entry1  anything;
+}
+
+
+// * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * * //