All lines are stored in the vector<string> base class.  When StoreIndices was
specified the 0-based line indices of lines were stored in d_index.

The member open clears the current contents and reinitializes all with the
info read from the new file.

At construction time comment handling (keep comment / remove comment),
case-sensitive searching (sensitive / insensitive) and index storage (store /
don't store) can be specified.

It can't be modified with the open member, but overloaded assignment is
supported and comment and letter case handling can be modified by set-members.

The begin() and end() members return the iterators into the vector of
configuration file lines (with continuation lines merged, and comment
optionally removed).

find(target):
To find an element `target' in a configuration file find(target) can be used.
It it handles case insensitive searches and uses findRE after replacing each
character in target by an escape character. This turns the special RE
characters into normal characters so findRE can be used fo the matching.

findRE(target):
here an RE is used to perform the match. It visits alle stored lines of the
configuration file returning the first line for which the regular expression
matched (using the `match' function in configfile.fh).

findKey(key, count):
find the value of the `count-th' occurrence of 'key value'. It calls
searchFor to find the count-th occurrence of key. findKeyTail acts similarly,
but doesn't allow anything to appear beyond value.

searchfor(key, pattern, count):
