Multiple features: source path substitution, relative source filename display, custom HTML report title

[aallrd]

Hello, I would like to contribute the below features:

• source path substitution
  • The source files used to build the application will not always be in the expected location.
  • This is the same feature as the gdb substitution path to locate source files on disk.
• relative source filename display
  • The full path of the source files can be long and meaningless (see above).
  • This feature allows to display only relative paths, removing a list of prefixes.
• custom HTML report title
  • Self explanatory, ability to change the title of the HTML report from the default "ValgrindCI report"