code cleanup.
code cleanup.

more or less in order of appearance:

  - no need to raise an error after cmds.error() since this already stops execution.
  - renamed a few functions to adhere to Python naming convention.
  - factorized the code in write_transform().
  - write_transform() no longer emit redundant <scaling> or <matrix> elements.
  - check that the number of motion samples is valid in a single place, when we retrieve the value from the UI.
  - cleaned up information, warning and error messages.
  - removed unnecessary print messages.
  - removed dead code.
  - eliminated redundant cmds.currentTime() calls.
  - fixed typos.

ckod3/mayaseed