patch 8.1.0615: get_tv function names are not consistent

Problem:    Get_tv function names are not consistent.
Solution:   Rename to tv_get.
diff --git a/src/proto/eval.pro b/src/proto/eval.pro
index 03c6506..bc6808c 100644
--- a/src/proto/eval.pro
+++ b/src/proto/eval.pro
@@ -82,13 +82,13 @@
 void free_tv(typval_T *varp);
 void clear_tv(typval_T *varp);
 void init_tv(typval_T *varp);
-varnumber_T get_tv_number(typval_T *varp);
-varnumber_T get_tv_number_chk(typval_T *varp, int *denote);
-float_T get_tv_float(typval_T *varp);
-char_u *get_tv_string(typval_T *varp);
-char_u *get_tv_string_buf(typval_T *varp, char_u *buf);
-char_u *get_tv_string_chk(typval_T *varp);
-char_u *get_tv_string_buf_chk(typval_T *varp, char_u *buf);
+varnumber_T tv_get_number(typval_T *varp);
+varnumber_T tv_get_number_chk(typval_T *varp, int *denote);
+float_T tv_get_float(typval_T *varp);
+char_u *tv_get_string(typval_T *varp);
+char_u *tv_get_string_buf(typval_T *varp, char_u *buf);
+char_u *tv_get_string_chk(typval_T *varp);
+char_u *tv_get_string_buf_chk(typval_T *varp, char_u *buf);
 dictitem_T *find_var(char_u *name, hashtab_T **htp, int no_autoload);
 dictitem_T *find_var_in_ht(hashtab_T *ht, int htname, char_u *varname, int no_autoload);
 hashtab_T *find_var_ht(char_u *name, char_u **varname);