begin audit of R code model
fix some indentation edge cases
start at index 1 here (since we -1 later)
continuation indent undesired when vertically aligning
tweak; add new test
naked if/else indentation fixes
insertion behaviour for other bracket pairs
comments from @jmcphers
Merge pull request #251 from rstudio/bugfix/r-codemodel-audit

Audit + clean up token walking code in the R code model