Use relative paths for files under current working directory

[jonkoops]

Uses relative paths for files under the current working directory, for example:

Before

There are 4 handle(s) keeping the process running

# Timeout
/path/to/project/example.js:6  - setInterval(() => {}, 1000)
/path/to/project/example.js:10 - startServer()

# TCPSERVERWRAP
/path/to/project/example.js:7  - server.listen(0)
/path/to/project/example.js:10 - startServer()

# Timeout
/path/to/project/example.js:6  - setInterval(() => {}, 1000)
/path/to/project/example.js:11 - startServer()

# TCPSERVERWRAP
/path/to/project/example.js:7  - server.listen(0)
/path/to/project/example.js:11 - startServer()

After

There are 4 handle(s) keeping the process running

# Timeout
example.js:6  - setInterval(() => {}, 1000)
example.js:10 - startServer()

# TCPSERVERWRAP
example.js:7  - server.listen(0)
example.js:10 - startServer()

# Timeout
example.js:6  - setInterval(() => {}, 1000)
example.js:11 - startServer()

# TCPSERVERWRAP
example.js:7  - server.listen(0)
example.js:11 - startServer()

If a path is outside of the current working directory the full absolute path will be used instead.

[jonkoops]

@mafintosh I am gonna merge this one in, if you have any objections against these functional changes let me know and I will revert the work.