Add TBC sequence

This sequence clears tab stops in the terminal. If the argument is not present
or is zero, then removes the tab stop of the current horizontal position. If
the argument is 3 then removes all the tab stops of the terminal. It was
necessary modify the terminfo entry tbc, because it has \E[2g instead of the
correct \E[3g.

Signed-off-by: Roberto E. Vargas Caballero <k0ga@shike2.com>
---
 st.c    |   12 ++++++++++++
 st.info |    2 +-
 2 files changed, 13 insertions(+), 1 deletion(-)

1 files changed, 12 insertions, 0 deletions

diff --git a/st.c b/st.c
index 4b7e4eb..b7dfd55 100644
--- a/st.c
+++ b/st.c
@@ -1203,6 +1203,18 @@ csihandle(void) {
 		DEFAULT(escseq.arg[0], 1);
 		tmoveto(0, term.c.y-escseq.arg[0]);
 		break;
+	case 'g': /* TBC -- Tabulation clear */
+		switch (escseq.arg[0]) {
+		case 0: /* clear current tab stop */
+			term.tabs[term.c.x] = 0;
+			break;
+		case 3: /* clear all the tabs */
+			memset(term.tabs, 0, term.col * sizeof(*term.tabs));
+			break;
+		default:
+			goto unknown;
+		}
+		break;
 	case 'G': /* CHA -- Move to <col> */
 	case '`': /* XXX: HPA -- same? */
 		DEFAULT(escseq.arg[0], 1);