gagolews/stringi: stringi_1.6.2

[BACKWARD INCOMPATIBILITY] In stri_enc_list(), simplify now defaults to TRUE. [NEW FEATURE] #425: The outputs of stri_enc_list(), stri_locale_list(), stri_timezone_list(), and stri_trans_list() are now sorted. [NEW FEATURE] #428: In stri_flatten, na_empty=NA now omits missing values. [BUILD TIME] #431: Pre-4.9.0 GCC has ::max_align_t, but not std::max_align_t, added a (possible) workaround, see the INSTALL file. [BUGFIX] #429: stri_width() misclassified the width of certain code points (including grave accent, Eszett, etc.); General category Sk (Symbol, modifier) is no longer of width 0, UCHAR_EAST_ASIAN_WIDTH of U_EA_AMBIGUOUS is no longer of width 2. [BUGFIX] #354: ALTREP CHARSXPs were not copied, and thus could have been garbage collected in the so-called meanwhile (with thanks to @jimhester)