Fix World Age Problem with Generated Functions

[pulsipher]

The new parameter function workflow that sometimes generates new functions to handle extra arguments can run into world age problems. This fixes that.

[codecov]

Codecov Report

❗ No coverage uploaded for pull request base (master@ffa3b53). Click here to learn what that means.
The diff coverage is 100.00%.

@@            Coverage Diff            @@
##             master     #123   +/-   ##
=========================================
  Coverage          ?   99.92%           
=========================================
  Files             ?       33           
  Lines             ?     6607           
  Branches          ?        0           
=========================================
  Hits              ?     6602           
  Misses            ?        5           
  Partials          ?        0           

Impacted Files	Coverage Δ
src/InfiniteOpt.jl	100.00% <ø> (ø)
src/TranscriptionOpt/model.jl	100.00% <100.00%> (ø)
src/expressions.jl	100.00% <100.00%> (ø)
src/general_variables.jl	99.39% <100.00%> (ø)

---

Continue to review full report at Codecov.

Legend - Click here to learn more
Δ = absolute <relative> (impact), ø = not affected, ? = missing data
Powered by Codecov. Last update ffa3b53...0cd2a4d. Read the comment docs.