This is just to let you know that there is a possible problem in the horizon. I am writing a book and noticed that my ggtern examples had stopped working when I updated 'ggplot2' to the development version now in Github. I am not sure if this is a bug that needs to be fixed in your package or in 'ggplot2' itself.
The current development version of 'ggplot2' breaks ggtern, the example given below results in the following message:
Error in f(..., self = self) : unused argument (<environment>)
library(ggtern) test.data <- data.frame(x = 0.5, y = 0.5, z = 0.5) ggtern(data=test.data, aes(x=R, y=G, z=B)) + geom_point()
R version 3.4.1 (2017-06-30) Platform: x86_64-w64-mingw32/x64 (64-bit) Running under: Windows >= 8 x64 (build 9200) Matrix products: default locale:  LC_COLLATE=English_United Kingdom.1252 LC_CTYPE=English_United Kingdom.1252  LC_MONETARY=English_United Kingdom.1252 LC_NUMERIC=C  LC_TIME=English_United Kingdom.1252 attached base packages:  stats graphics grDevices utils datasets methods base other attached packages:  ggtern_2.2.1 ggplot2_188.8.131.5200 devtools_1.13.3 loaded via a namespace (and not attached):  Rcpp_0.12.12 magrittr_1.5 MASS_7.3-47 munsell_0.4.3  colorspace_1.3-2 lattice_0.20-35 rlang_0.1.1 stringr_1.2.0  plyr_1.8.4 tools_3.4.1 grid_3.4.1 gtable_0.2.0  withr_2.0.0 yaml_2.1.14 lazyeval_0.2.0 digest_0.6.12  tibble_1.3.3 bayesm_3.1-0.1 latex2exp_0.4.0 gridExtra_2.2.1  tensorA_0.36 energy_1.7-0 compositions_1.40-1 memoise_1.1.0  robustbase_0.92-7 stringi_1.1.5 compiler_3.4.1 DEoptimR_1.0-8  scales_0.4.1.9002 boot_1.3-19 proto_1.0.0 >
You may want to discuss this with the maintainer of 'ggplot2' in good time.