Remove project int types: Case short_u: Replace with uint16_t.

- Replace short_u with uint16_t (same size, should give no problems).
- When possible, remove explicit downcasts so that they are found when
  flag -Wconversion enabled.
- Remove short_u typedef.

Requested in #459.

src/buffer_defs.h

@@ -378,7 +378,7 @@ typedef struct {
   synstate_T  *b_sst_firstfree;
   int b_sst_freecount;
   linenr_T b_sst_check_lnum;
-  short_u b_sst_lasttick;       /* last display tick */
+  uint16_t b_sst_lasttick;      /* last display tick */
 
   /* for spell checking */
   garray_T b_langp;             /* list of pointers to slang_T, see spell.c */
@@ -774,7 +774,7 @@ struct tabpage_S {
  */
 typedef struct w_line {
   linenr_T wl_lnum;             /* buffer line number for logical line */
-  short_u wl_size;              /* height in screen lines */
+  uint16_t wl_size;             /* height in screen lines */
   char wl_valid;                /* TRUE values are valid for text in buffer */
   char wl_folded;               /* TRUE when this is a range of folded lines */
   linenr_T wl_lastlnum;         /* last buffer line number for logical line */

src/memline.c

@@ -100,9 +100,9 @@ struct pointer_entry {
  * A pointer block contains a list of branches in the tree.
  */
 struct pointer_block {
-  short_u pb_id;                /* ID for pointer block: PTR_ID */
-  short_u pb_count;             /* number of pointers in this block */
-  short_u pb_count_max;         /* maximum value for pb_count */
+  uint16_t pb_id;               /* ID for pointer block: PTR_ID */
+  uint16_t pb_count;            /* number of pointers in this block */
+  uint16_t pb_count_max;        /* maximum value for pb_count */
   PTR_EN pb_pointer[1];         /* list of pointers to blocks (actually longer)
                                  * followed by empty space until end of page */
 };
@@ -115,7 +115,7 @@ struct pointer_block {
  * etc. Thus the order of the lines is the opposite of the line number.
  */
 struct data_block {
-  short_u db_id;                /* ID for data block: DATA_ID */
+  uint16_t db_id;               /* ID for data block: DATA_ID */
   unsigned db_free;             /* free space available */
   unsigned db_txt_start;        /* byte where text starts */
   unsigned db_txt_end;          /* byte just after data block */
@@ -3011,8 +3011,7 @@ static bhdr_T *ml_new_ptr(memfile_T *mfp)
   pp = (PTR_BL *)(hp->bh_data);
   pp->pb_id = PTR_ID;
   pp->pb_count = 0;
-  pp->pb_count_max = (short_u)((mfp->mf_page_size - sizeof(PTR_BL))
-                               / sizeof(PTR_EN) + 1);
+  pp->pb_count_max = (mfp->mf_page_size - sizeof(PTR_BL)) / sizeof(PTR_EN) + 1;
 
   return hp;
 }

src/normal.c

@@ -218,7 +218,7 @@ typedef void (*nv_func_T)(cmdarg_T *cap);
 static const struct nv_cmd {
   int cmd_char;                 /* (first) command character */
   nv_func_T cmd_func;           /* function for this command */
-  short_u cmd_flags;            /* NV_ flags */
+  uint16_t cmd_flags;           /* NV_ flags */
   short cmd_arg;                /* value for ca.arg */
 } nv_cmds[] =
 {

src/spell.c

@@ -568,7 +568,7 @@ typedef struct langp_S {
 static char_u   *int_wordlist = NULL;
 
 typedef struct wordcount_S {
-  short_u wc_count;                 // nr of times word was seen
+  uint16_t wc_count;                // nr of times word was seen
   char_u wc_word[1];                // word, actually longer
 } wordcount_T;
 
@@ -4252,7 +4252,7 @@ struct wordnode_S {
   // In the soundfolded word tree "wn_flags" has the MSW of the wordnr and
   // "wn_region" the LSW of the wordnr.
   char_u wn_affixID;            // supported/required prefix ID or 0
-  short_u wn_flags;             // WF_ flags
+  uint16_t wn_flags;            // WF_ flags
   short wn_region;              // region mask
 
 #ifdef SPELL_PRINTTREE
@@ -7236,7 +7236,7 @@ put_node (
           // associated condition nr (stored in wn_region).  The
           // byte value is misused to store the "rare" and "not
           // combining" flags
-          if (np->wn_flags == (short_u)PFX_FLAGS)
+          if (np->wn_flags == (uint16_t)PFX_FLAGS)
             putc(BY_NOFLAGS, fd);                       // <byte>
           else {
             putc(BY_FLAGS, fd);                         // <byte>

src/syntax_defs.h

@@ -69,8 +69,8 @@ typedef struct attr_entry {
     } term;
     struct {
       /* These colors need to be > 8 bits to hold 256. */
-      short_u fg_color;                 /* foreground color number */
-      short_u bg_color;                 /* background color number */
+      uint16_t fg_color;                /* foreground color number */
+      uint16_t bg_color;                /* background color number */
     } cterm;
   } ae_u;
 } attrentry_T;

src/types.h

@@ -15,7 +15,6 @@
  * already defined, so we use char_u to avoid trouble.
  */
 typedef unsigned char char_u;
-typedef unsigned short short_u;
 typedef unsigned int int_u;
 
 #endif /* NEOVIM_TYPES_H */