Improved font caching

I made a patch that improves the performance of font caching mechanism.
This is based on a funny behaviour of FontConfig: it was handling
FcCharSet in a somewhat unexpected way.

So, we are currently adding "a character" to a new FcCharSet, and then
add it to a FcPattern. However, if we toss the FcPattern to FontConfig,
it loads the entire language(charset) that contains the character we
gave. That is, we don't always have to load a new font for each unknown
character. Instead, we can reused cached fonts, and this significantly
reduces the number of calls to extremely slow FontConfig matching
functions.

One more thing. I found that, in libXft, there's a function called
XftCharExists. XftCharIndex internally calls this function, and
does more stuffs if the character does exist. Since the returned index
is never used in st, we should call XftCharExists instead of
XftCharIndex. Please note that I already made this change in the patch.
Add RGB color definition

This patch uses the bit 24 in the color descriptor as an indicator
of RGB color, so we can take the values and generating the XftColour
directly in xdraws.
Reload colors in reset

Colors definition can be changed using a OSC sequence, so
we have to reload them if we want be sure all the colors
are the correct.

Could be desirable free the colors allocated due to rgb
colors and inverse colors (XftColorAllocValues in xdraws),
but it is impossible due we use the same structure for all
of them.
Use character size scaling factors

The bounding boxes for characters can be scaled using "cwscale" and "chscale"
to scale the width and height respectively.
Fix blink mode check

ATTR_BLINK is an attribute for a Glyph and will not be set in term.mode.
Fixed memory leak in xsettitle().
Fix signess of tdefcolor

tdefcolor() returns -1 on error, while its return type is
unsigned long. At the same time, line 1724 and 1731 are checking the
positivity of its unsigned return value.
Add terminfo definitions for terminals with meta key

Some programs don't check the value of km and use smm and rmm
capabilites, and they cause the terminal change to meta enabled
mode even in cases where is not desirable.

Allmost all people is using the terminal waiting that meta sends
escape, so rmm and smm are not needed. If someone needs meta
sets 8 bit he can use the correct terminfo definition in TERM.
Correcting the bitmask value check.
Tmux is using C-b by default.

Thanks for noticing Fidel Barrera Cruz!
Regarding commit 7e3cff3

Hello.

I reviewed and tested commit 7e3cff3, and made a patch that fixes some
problems in it.

1. There's a semicolon after an if statement, which is obviously a
typo.

2. The current way of calculating text position in "xdraws" yields
inconsistent results in some cases. This is due to the use of
"font->width", which varies. Instead, "xw.cw" has to be used as the
character width.

Sincerely,
Eon
Correctly initialize altscreen when defaultbg is not 0.

The alternate screen is not properly initialized when st starts. To see
this, set defaultbg in config.h to anything other than 0 (for example, swap
defaultfg and defaultbg), and run:

./st -e sh -c 'tput smcup; read'

You should see that the top-left 80x24 rectangle is black (or whatever
colorname[0] is), while the rest of the screen (if any) has the desired
colorname[defaultbg] color.

The attached patch fixes this by initializing term.c.attr in tnew() before
calling tresize(). It also removes the unnecessary xcalloc() calls, which
misled me on this bug hunt since it is really tclearregion() which
initializes term.lines and term.alt in tresize().
Adding some contributors. Thanks to you all!
Wide character support.

Thanks "Eon S. Jeon" <esjeon@hyunmu.am>!
Add audible bell

\a is the character for bell, and st is only marking the window as urgent
if it is not active. This patch adds an audible bell which can be disable
with bellvolume variable.

Signed-off-by: Christoph Lohmann <20h@r-36.net>
Default volume of the bell is 0.
Fix some bugs in mouse tracking logic

* Button number in X10 mode:

  I believe the button - 1 came from "C b is button - 1" from [0].
  However, above this section, it states

    "Normally, parameters (such as pointer poisition and button number)
     for all mouse tracking escape sequences generated by xterm encode
     numeric parameters in a single character as value+32. For example, !
     specifies the value 1."

  Also, from the description of SGR,

    "The encoded button value in this case does not add 32 since that
     was useful only in the X10 scheme for ensuring that the byte
     containing the button value is a printable code."

  This suggests that we should still add 32 to the button value when in
  MODE_MOUSEX10.

* No button release reporting in X10 mode:

    "X10 compatibility mode sends an escape sequence only on button press,
     encoding the location and the mouse button pressed."

* Fix MODE_MOUSEMOTION:

  Currently, motion reporting is skipped when oldbutton == 3
  (corresponding to no button being pressed). However, oldbutton is
  only set on a button press, which will never be 3.

[0]: http://invisible-island.net/xterm/ctlseqs/ctlseqs.html
Add bracketed paste mode

This patch enables bracketed paste mode (
http://invisible-island.net/xterm/ctlseqs/ctlseqs.html#Bracketed%20Paste%20Mode
).

It's mainly useful for text editors to disable line wrapping and auto
indentation when text is being pasted, rather than typed from keyboard.

On the emulator side, it is supported by at least xterm, urxvt,
gnome-terminal, putty, iterm2; and I have a patch for konsole.

On the application side, vim can be configured easily to handle this, and
I have pending patches for mcedit and joe. Probably many others also
support it.
Fix core in multi-line selection on OpenBSD

OpenBSD 5.3 amd64 release version with the most current st
version from git, crash and dump core when selecting multiple
lines whith the cursor.  This happens, because on line 964
of st.c (gp-1)->mode is accessed, although gp is still
pointing at the beginning of the array term.line[y] (see
line 939 for initialization of gp).
Add DSR cursor position sequence