Add a new DynamicMeter class for runtime Meter extension

This commit is based on exploratory work by Sohaib Mohamed.
The end goal is two-fold - to support addition of Meters we
build via configuration files for both the PCP platform and
for scripts ( https://github.com/htop-dev/htop/issues/526 )

Here, we focus on generic code and the PCP support.  A new
class DynamicMeter is introduced - it uses the special case
'param' field handling that previously was used only by the
CPUMeter, such that every runtime-configured Meter is given
a unique identifier.  Unlike with the CPUMeter this is used
internally only.  When reading/writing to htoprc instead of
CPU(N) - where N is an integer param (CPU number) - we use
the string name for each meter.  For example, if we have a
configuration for a DynamicMeter for some Redis metrics, we
might read and write "Dynamic(redis)".  This identifier is
subsequently matched (back) up to the configuration file so
we're able to re-create arbitrary user configurations.

The PCP platform configuration file format is fairly simple.
We expand configs from several directories, including the
users homedir alongside htoprc (below htop/meters/) and also
/etc/pcp/htop/meters.  The format will be described via a
new pcp-htop(5) man page, but its basically ini-style and
each Meter has one or more metric expressions associated, as
well as specifications for labels, color and so on via a dot
separated notation for individual metrics within the Meter.

A few initial sample configuration files are provided below
./pcp/meters that give the general idea.  The PCP "derived"
metric specification - see pmRegisterDerived(3) - is used
as the syntax for specifying metrics in PCP DynamicMeters.

1 files changed, 3 insertions, 1 deletions

diff --git a/CommandLine.c b/CommandLine.c
index 60582dcf..4a721a3d 100644
--- a/CommandLine.c
+++ b/CommandLine.c
@@ -22,6 +22,7 @@ in the source distribution for its full text.
 
 #include "Action.h"
 #include "CRT.h"
+#include "DynamicMeter.h"
 #include "Hashtable.h"
 #include "Header.h"
 #include "IncSet.h"
@@ -288,7 +289,8 @@ int CommandLine_run(const char* name, int argc, char** argv) {
    Process_setupColumnWidths();
 
    UsersTable* ut = UsersTable_new();
-   ProcessList* pl = ProcessList_new(ut, flags.pidMatchList, flags.userId);
+   Hashtable* dm = DynamicMeters_new();
+   ProcessList* pl = ProcessList_new(ut, dm, flags.pidMatchList, flags.userId);
 
    Settings* settings = Settings_new(pl->cpuCount);
    pl->settings = settings;