Allow underscores in dust::name and similar

[richfitz]

See mrc-ide/odin.dust#98 for the trigger. We just fall back to using dust for the dll name which should work fine. For packages, this is not a problem at all.

Fixes #358
Fixes mrc-ide/odin.dust#98

[codecov]

Codecov Report

Merging #359 (fb98452) into master (24f843d) will not change coverage.
The diff coverage is 100.00%.

❗ Current head fb98452 differs from pull request most recent head 7f7d8fe. Consider uploading reports for the commit 7f7d8fe to get more accurate results

@@            Coverage Diff            @@
##            master      #359   +/-   ##
=========================================
  Coverage   100.00%   100.00%           
=========================================
  Files           64        64           
  Lines         3487      3488    +1     
=========================================
+ Hits          3487      3488    +1     

Impacted Files	Coverage Δ
R/utils.R	100.00% <ø> (ø)
R/compile.R	100.00% <100.00%> (ø)
R/metadata.R	100.00% <100.00%> (ø)

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[chvandorp]

Hi Rich, I installed the i358-underscore branch and tried compiling a model with odin.dust::odin_dust. Underscores in filenames now work fine. However, I was able to come up with some other annoying filenames, but perhaps that's for another issue.

odin.dust::odin_dust("odin_dust_test(1).txt") ## causes error in R script
odin.dust::odin_dust("odin_dust.test.txt") ## causes C++ compilation error
odin.dust::odin_dust("odin_dust_test_missing.txt") ## if the file is missing, the warning does not show the filename

Thanks!

[richfitz]

Thanks for these examples @chvandorp; I've fixed these in odin (see mrc-ide/odin#254, allow-parens, version 1.3.3). With that installed, all 3 of your examples behave much better