Continued refactoring of connection implementation.

- Moved DelegateRConnection and subclasses into separate files (for better overview).
- Increased code sharing of readLines, readChar, readBin (same for write) by providing standard implementation in the delegate classes. Hence, implementation of, for example, named pipes (FIFOs) is almost trivial.
- Fixed some bug in SeekableMemoryByteChannel and changed behavior if a byte array is provided in the constructor.
- Implemented push back reset when seeking.

Added initial test class for FIFOs and added tests to file and text connections.
Implemented function "fifo" for working with named pipes.