ENH: rationalize dictionary access methods

- use keyType::option enum to consolidate searching options.
  These enumeration names should be more intuitive to use
  and improve code readability.

    Eg,   lookupEntry(key, keyType::REGEX);
    vs    lookupEntry(key, false, true);

  or

    Eg,   lookupEntry(key, keyType::LITERAL_RECURSIVE);
    vs    lookupEntry(key, true, false);

- new findEntry(), findDict(), findScoped() methods with consolidated
  search options for shorter naming and access names more closely
  aligned with other components. Behave simliarly to the
  methods lookupEntryPtr(), subDictPtr(), lookupScopedEntryPtr(),
  respectively. Default search parameters consistent with lookupEntry().

    Eg, const entry* e = dict.findEntry(key);
    vs  const entry* e = dict.lookupEntryPtr(key, false, true);

- added '*' and '->' dereference operators to dictionary searchers.

src/parallel/decompose/decompositionMethods/multiLevelDecomp/multiLevelDecomp.C

@@ -68,9 +68,9 @@ void Foam::multiLevelDecomp::createMethodsDict()
     if
     (
         // non-recursive, no patterns
-        coeffsDict_.readIfPresent("method", defaultMethod, false, false)
+        coeffsDict_.readIfPresent("method", defaultMethod, keyType::LITERAL)
         // non-recursive, no patterns
-     && coeffsDict_.readIfPresent("domains", domains, false, false)
+     && coeffsDict_.readIfPresent("domains", domains, keyType::LITERAL)
     )
     {
         // Short-cut version specified by method, domains only
@@ -169,14 +169,14 @@ void Foam::multiLevelDecomp::createMethodsDict()
             (
                 iter().isDict()
                 // non-recursive, no patterns
-             && iter().dict().found("numberOfSubdomains", false, false)
+             && iter().dict().found("numberOfSubdomains", keyType::LITERAL)
             )
             {
                 // No method specified? can use a default method?
 
                 const bool addDefaultMethod
                 (
-                    !(iter().dict().found("method", false, false))
+                    !(iter().dict().found("method", keyType::LITERAL))
                  && !defaultMethod.empty()
                 );