Change 'char *' to 'const char *' in headers included by plugins.

The change propagate to several classes using the values.
This get rid of all warnings in the colors plugin, and several
warnings in other plugins.

This reduce the amount of warnings and bring the code closer to HV 4.5.
Enable format related compiler warnings and errors.

Compile by default with -Wformat -Werror=format-security to
ensure that bugs that would break hardening build on Debian are not
introduced in the code.
Enable setting the required kernel.shmmax at first run (under debian)

This patch allows the setting the required kernel.shmmax at first run (under debian).
Without it, cinelerra will ask for the correct kernel.shmmax after
the first installation which is fairly confusing for the user.
Make BC_WindowBase::lock_window() argument 'const char*', not 'char *'.

This get rid of lots of warnings and bring the code closer to HV 4.5.
Make update_caption() and MWindow::load_filenames argument 'const char *'.

Fixes the last compiler warnings in the suv plugin and bring the code
closer to HV 4.5.
Fix: removed CR-s from mwindow.h

For some reason this file was formatted as a DOS file
Change BC_TextBox to use 'const char *' and not 'char *' in update() and ctor

The BC_TextBox class is used several times with string constants in
the code, causing compiler warnings.  This get rid of the warning and
bring the code closer to HV 4.5
Change FFT::do_fftw_inplace() to not return a value

Get rid of a compiler warning by changing the return type for
FFT::do_fftw_inplace() from 'int' to 'void', as the function do not
currently return a value and none of its callers expect it to do so.
Use the j modifier when formatting int64_t types.

Several places where int64_t is formatted or scanned, the wrong
format specification is used.  Use the j modifier to ensure (u)int64_t
is handled correctly, and to get rid of compiler warnings about
incorrect formatting.
Incremented the year of copyright message
Make sure to not use pointer after free in quicktime

Break out of the for loop when avcodec_open() fail and the
quicktime_ffmpeg_t object is released, to make sure the released
memory isn't accessed after free.  Fixes Coverity CID 59619.
Make VFrame methods get_next_effect() and get_prev_effect return 'const char*', not 'char *'.

This get rid of two compiler warnings and bring the code closer to HV 4.5.
Change suffix_to_type_t::suffix type to 'const char *'

An array of that type is initialized using constant strings.  This
change get rid of some of the warnings and bring the code closer to HV
4.5.
Fixed zeroing frame data in VFrame::clear_frame()

Fixed buffer overflow while clearing YUV420P buffer.
Use calculate_data_size for calculating the buffer size.
Replaced deprecated bzero with memset.
Print usage info from pngtoh when called without arguments

It is hard to figure out what pngtoh do without reading the source or
running strace on the binary.  Here is a patch to output some usage
information when it is called without arguments.
Merge branch 'master' into from-cinelerra-hv-4.5-const-plugin-suv

Fixed conflicts:
	cinelerra/mwindow.h