Change if-statement style

[casperklein]

Description

Change if-statement style from

if [[ ${#} -lt 3 ]]
then
  _log 'error' 'At least three parameters must be given'
  __usage
  exit 1
fi

to

if [[ ${#} -lt 3 ]]; then
  _log 'error' 'At least three parameters must be given'
  __usage
  exit 1
fi

Fixes #3302

Planned follow up style changes:

• while
• until
• function

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Improvement (non-breaking change that does improve existing functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my own code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation (README.md or the documentation under docs/)
• If necessary I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes

[georglauterbach]

Makes my heart bleed a bit 😝