Eliminate package warnings:
    - Temporary fix for missing documentation
    - Remove 'as.mle' usage
    - Remove dead code
    - Importance sampler cleanup
    - Importance sampler: sample confidence interval
    - Status of package check: 0 warnings + 4 notes
Remove final .so extensions in tmb_examples
Merge branch 'master' into bias_correct
Extend importance sampler to calulate mean of any function,
and fix bug in 'sdreport' when ad-reporting mulitple values with only one fixed effect.
sdreport: option to importance sample unbiased estimates