Now, everything is again byte-based (even in a text-mode connection) and the read bytes are then encoded at once.
This makes the code much cleaner.
However, this assumes that a multi-byte character cannot contain any of the byte signatures of NUL '0x00' or line feed '0x0A'.
But I haven't seen this in the UTF-8/UTF-16 tables.

Fixed issue when setting the r/w seek position in a binary-mode file connection.

Improved implementation of file read-write access; appending was not implemented.
However, currently experiencing some performance issues.

Fixed unit test issue: Used the system temp path in a test case which is different for other platforms.
Sorry for that.

Refined a test case.

Fixed serious bug during decoding: Did not properly use the decoder when reading single 'elements' from a connection using method 'getc'. An element is either a character or a byte depending on the connection mode text or binary, respectively.
Now, a stream decoder is created on demand and used for any subsequent character-based reading.
As in GnuR, mixing binary- and text-based reading and writing leads to undefined behavior since the decoder may already have consumed some bytes.

Removed unnecessary implementation of deleting a temp file since there was already support for this.

Refactored unit tests to not use temp dir (does not work reliably).

Fixed bug in class DelegateReadWriteRConnection: Did not properly return the output stream for compatibility.
Ignored a test using JUnit's Ignore annotation.

Added method 'ByteBuffer getChannel()' to interface RConnection and therefore exposing the unterlying channel for FastR internal use.
Removed fall-through cases in FileConnections.

Replaced "RError.error(this..." by "RError.error(RError.SHOW_CALLER...".
Implemented handling of flag 'raw' when opening files.
Added a test for this.
Fixed warning in class ConnectionFunctions.

Refactored base classes RConnection, BaseRConnection, and DelegateRConnection to strictly seperate the concerns.
BaseRConnection now stores "session data" whereas a delegate connection performs the I/O operation.
RConnection is now just an interface defining common operations.

Merged tests for raw connections into TestConnections.

Fixed checkstyle errors.

Implemented non-blocking/text-mode behavior of function "readLines" (silently pushes back incomplete final lines).
Refactored all delegate connection implementations to be based on a channel (again).