Look at NI instead of PRI in ps output on Linux

The PRI field is the Linux kernel scheduling priority which is
different from the niceness of a process (which is what a system
adminitrator and policy-writer is likely to want to select upon). This
value is almost always larger than 20, so it isn't selectable if the
defined range per the documentation is -20,+20 anyway.
cosmetic change
Checking for ioctl() return code in GetMacAddress()
Keep loopback interfaces, closes #1112
Don't grab mac address on interfaces having IFF_LOOPBACK flag
Add GetInterfaceFlags() to get NIC flags
Check for missing close brace '{' for body statements + 3 unit tests
small typo in commands_intro, missing "
Yr2009 is not true anymore, change to cfengine class
this is a basic example, it should run without modification
make basic examples in array section self-contained + typo
make bundle edit_line example in Pattern matching and referencing section self-contained
add file content to explain Commenting lines section
Short-cut Epimenides if the string doesn't change.
Allow spaces in variable names during expansion

Improves RM #1970.

There are other cases of scanf using %[^.].%s, mostly in function
evaluation that this does not cover.
Fixed error checking for fgets().

The correct way to check for error is to inspect either errno or
ferror(). Before we tried to rely on breaking out of the loop using
feof(), but this is incorrect for directories, which can be opened,
but will never return feof() == true, nor a successful read.

Fixes issue 2451. The original issue is only in one place, but error
checking was improved in many places.
Don't proceed with file operations when we know the file doesn't exist

Fixes issue 2448.
Merge pull request #547 from kacfengine/issue-2448

Don't proceed with file operations when we know the file doesn't exist
Merge pull request #546 from kacfengine/issue-2451

Fixed error checking for fgets().
Merge pull request #543 from jremond/typo_doc_ref

Typo correction and add elements in reference documentation