Updates to some BURT related functions in the EPICS sequencer.

• Remove plain char arrays from writeTable2File, replace with fixed_string.
• Rework encodeBURTString to take fixed_string inputs
  • Update it to have no failure cases. This is done by replacing pointers with references and putting compile time checks in on input lengths.
  • Put encodeBURTString under test.
• Minor updates to fixed_string
  • introduce begin()/end() for range for loop support and empty() to clarify code.
  • introduce an operator+=(char) for appending a character at a time.
• Updates to the parseLine function
  • put parseLine under test
  • Fixed an overflow issue in parseLine when there is a quoted word that is longer than the output buffers.
  • Fixed an issue with parsing where the quotes were returned in the output if the first word was quote escaped.
  • Reworked it to use fixed strings and vectors instead of 6 char* out parameters.
• Moved encodeBURTString and parseLine to burt_file.hh
  • Put them in a BURT namespace
  • Renamed BURT::encodeBURTString -> BURT::encodeString