userspace/libsinsp/filter: make next_operand return vector<char>

Modify sinsp_filter::next_operand to handle operand which contains
the NUL terminator.
userspace/libsinsp/filter*: modify parse_filter_value to accept len

When the filter value is binary, we need to pass the length of the
value.
userspace/libsinsp/filter*: extend rawval_to_string to accept PT_BYTEBUF
userspace/libsinsp/filter*: evt.buffer return raw_value when m_is_compare
userspace/libsinsp/filterchecks: some refactoring
userspace/libsinsp/filter*: transform evt.buffer in PT_BYTEBUF
userspace/libsinsp: remove old code
userspace: remove some trailing whitespace
userspace/libsinsp/parsers.cpp: filter out events about sysdig digs sysdig
userspace: add option to enable sysdig to capture events about itself
userspace/libsinsp/parsers: fix compile error on windows
[28] Complete quoting for parameters of some CMake commands

Adds quotes where applicable for variables inside of the CmakeLists
files
Merge pull request #83 from kristopolous/28-complete-quoting-for-parameters-of-some-cmake-commands

[28] Complete quoting for parameters of some CMake commands. fixes #28
userspace/libsinsp/parsers: cache the current pid and get_thread_info
userspace/libsinsp: get thread info about a event only for live capture
Added spy_port.lua
[71] Detect in-tree build and fail

This commit will check to see if the file CMakeLists.txt exists in
the current directory and if so, will assume that the user is trying
to build in tree.

It will immediately fail and print out instructions on how to properly
build sysdig along with a shortened link to the wiki page for more
information.
Merge pull request #88 from kristopolous/71-detect-in-tree-build-and-fail

[71] Detect in-tree build and fail. fixes #71
userspace/sysdig: update man page with -D option
Merge pull request #87 from clausa/master

Added spy_port.lua