docs: typo fixes.
bugfix: when special chars appear in the nginx path, ngx-sample-bt, ngx-sample-lua-bt and ngx-pcrejit will run bad shell commands. thanks Dane Knecht for reporting the issue in #2.
ngx-sample-lua-bt: removed an unused variable.
feature: added new tool ngx-pcre-stats to analyze PCRE regex runtime performance statistically. thanks Dane Knecht for requesting this.
minor doc tweaks for ngx-pcre-stats.
ngx-pcre-stats: fixed a misleading error message. thanks Dane Knecht for reporting it.
feature: added the "-t <seconds>" command-line option to the ngx-pcre-stats tool to allow specifying the sampling period explicitly. thanks Dane Knecht for requesting this.
ngx-pcre-stats: no longer quote the regex text because there is seldom or never special chars in regexes.
feature: added the ngx-lua-bt tool to dump the current Lua backtrace in the current running Lua thread in a specified nginx worker process.
ngx-lua-bt: use the line number of "currentline" instead of "linedefined" in the Lua backtrace when the --lua51 option is specified.
ngx-sample-lua-bt: fixed a small bug when initializing the "nextframe" variable.
ngx-lua-bt: use "currentline" instead of "firstline" in the Lua-land backtraces when the --luajit20 option is specified.
ngx-lua-bt: hooked up ngx_http_lua_*, lua_*, and luaL_* for better coverage; also fixed the line number in the backtraces for std Lua 5.1 interpreter; updated docs a bit.
docs: updated the copyright years.
feature: added new tool ngx-sample-bt-vfs for sampling file I/O on the virtual file system level.