Added file headers to LineMatching.py and TestLineMatching.py.

Contains short description of the file's purpose and a link to the GitHub page.
Added Stack.py.

With file header. Contents to follow.
Implemented StackFrame class.

It is a container class for data parsed from a single line of a call stack.
Extended file description of Stack.py.

Now mentions source of data it contains.
Converted class attributes to instance attributes.

Just learned that any attribute 'attr' first mentioned immediately in
the class definition, as opposted to inside a methods such as __init__,
are shared among all class instances that haven't yet assigned to
'self.attr' from within a function.

Have therefore moved all instance variable declarations to inside
__init__.
Bit more whitespace between end of LineMatching.isErrorStart and LineMatching.isSourceStart.
Implemented Stack.

Contains a list of StackFrames and provides some helper methods for
manipulating that list.
Implemented Stack.getFrame.

Also added Stack.FROM_TOP and Stack.FROM_BOTTOM to select the side that
the given index should be relative to.
Changed method regular expression to include ',' and '&' while '(' and ')' was removed.
Updated TestLineMatching due to recent update in LineMatching.py

Added a comment describing the source of the expected numbers and a plan for
updating them.

Added support for the '--verbose' flag to the test to print the number of
matches for each pattern.
Added *.swp to .gitignore.

*.swp are Vim swap files.
Implemented ParsedError.
Test for ParsedError.

Creates a ParsedError from a Valgrind error log snippet. Currently no
validation of the created object.