patch 8.1.0105: all tab stops are the same

Problem:    All tab stops are the same.
Solution:   Add the variable tabstop feature. (Christian Brabandt,
            closes #2711)
diff --git a/src/proto/misc1.pro b/src/proto/misc1.pro
index 0e1d22e..58c3d3f 100644
--- a/src/proto/misc1.pro
+++ b/src/proto/misc1.pro
@@ -3,6 +3,7 @@
 int get_indent_lnum(linenr_T lnum);
 int get_indent_buf(buf_T *buf, linenr_T lnum);
 int get_indent_str(char_u *ptr, int ts, int list);
+int get_indent_str_vtab(char_u *ptr, int ts, int *vts, int list);
 int set_indent(int size, int flags);
 int get_number_indent(linenr_T lnum);
 int get_breakindent_win(win_T *wp, char_u *line);
diff --git a/src/proto/option.pro b/src/proto/option.pro
index 60a45e6..22c163d 100644
--- a/src/proto/option.pro
+++ b/src/proto/option.pro
@@ -60,6 +60,15 @@
 void save_file_ff(buf_T *buf);
 int file_ff_differs(buf_T *buf, int ignore_empty);
 int check_ff_value(char_u *p);
+int tabstop_set(char_u *var, int **array);
+int tabstop_padding(colnr_T col, int ts_arg, int *vts);
+int tabstop_at(colnr_T col, int ts, int *vts);
+colnr_T tabstop_start(colnr_T col, int ts, int *vts);
+void tabstop_fromto(colnr_T start_col, colnr_T end_col, int ts, int *vts, int *ntabs, int *nspcs);
+int tabstop_eq(int *ts1, int *ts2);
+int *tabstop_copy(int *oldts);
+int tabstop_count(int *ts);
+int tabstop_first(int *ts);
 long get_sw_value(buf_T *buf);
 long get_sts_value(void);
 void find_mps_values(int *initc, int *findc, int *backwards, int switchit);