Version 0.1.8

Fixes an issue that caused configure_exiftoolr() (and thus essentially all exiftoolr functionality) to fail on Windows machines that do not have Perl installed in a location findable by the exiftoolr:::configure_perl(). Thanks to Tom Yamashita for reporting this issue.
Adds tests (using the tinytest package).

Version 0.1.7

Fixes an issue that could cause configure_exiftoolr() to fail if the path to the ExifTool executable on a user’s computer contained any spaces. Now configure_exiftoolr() should work even if there are spaces in the path(s) to the user’s installation of Perl and/or their ExifTool executable or library. Thanks to Lafont Rapnouil Tristan for reporting the issue.

Fixes a problem likely to affect Linux users (but also any others relying on a local installation of Perl to execute calls to ExifTool), caused by the internal change in exif_call() in 0.1.5 from system() to system2(). Thanks to Daniel Baumgartner for bringing this to my attention.

Added a pipeline option to exif_read(), which allows users to direct the exif executable to output results in csv rather than json format. This is helpful for use with images whose metadata contains non-UTF-8-encoded characters. As is documented here, ExifTool’s JSON output does not properly handle non-UTF-8 character sets. Setting pipeline="csv" ensures that non-UTF-8 character sets are properly handled, as demonstrated in a new example in ?exif_read.

Fixed exif_read() to now allow repeated elements in args=. This can be necessary when (to take one example) a user needs to separately specify the encoding used in the image file names and in the tags respectively. Now, a call like the following works as it should:
```
exif_read(path = "myimage.jpg", 
          args = c("-charset", "exiftool=cp850", "-charset", "filename=cp1250"))
```

Failure of configure_exiftoolr() to find a local installation of ExifTool now throws an error rather than just a warning, preventing infinite recursion by exif_read() and exif_version().