mark functions and vars as static (#146)

the goal here to mark functions and variables not used outside the
translation unit as static. main reason for this is cleanliness. however
as a side-effect this can help compilers optimize better as it now has
guarantee that a certain function won't be called outside of that
translation unit.

one other side-effect of this is that accessing these vars/function from
config.h is now different.

if one wants to access a static var/func from different translation unit
in config.h, he would have to create a wrapper function under the right
ifdef. for static functions one would also need to forward declare it.
here's a dummy example of accessing the function `run_key_handler` from
config.h under _MAPPINGS_CONFIG

```
static void run_key_handler(const char *, unsigned);
bool send_with_ctrl(arg_t key) {
	run_key_handler(XKeysymToString(key), ControlMask);
	return false;
}
```

1 files changed, 5 insertions, 5 deletions

diff --git a/thumbs.c b/thumbs.c
index f518ecb..4ba96fa 100644
--- a/thumbs.c
+++ b/thumbs.c
@@ -38,7 +38,7 @@ Imlib_Image img_open(const fileinfo_t*);
 static char *cache_dir;
 extern const int fileidx;
 
-char* tns_cache_filepath(const char *filepath)
+static char* tns_cache_filepath(const char *filepath)
 {
 	size_t len;
 	char *cfile = NULL;
@@ -55,7 +55,7 @@ char* tns_cache_filepath(const char *filepath)
 	return cfile;
 }
 
-Imlib_Image tns_cache_load(const char *filepath, bool *outdated)
+static Imlib_Image tns_cache_load(const char *filepath, bool *outdated)
 {
 	char *cfile;
 	struct stat cstats, fstats;
@@ -76,7 +76,7 @@ Imlib_Image tns_cache_load(const char *filepath, bool *outdated)
 	return im;
 }
 
-void tns_cache_write(Imlib_Image im, const char *filepath, bool force)
+static void tns_cache_write(Imlib_Image im, const char *filepath, bool force)
 {
 	char *cfile, *dirend;
 	struct stat cstats, fstats;
@@ -200,7 +200,7 @@ CLEANUP void tns_free(tns_t *tns)
 	cache_dir = NULL;
 }
 
-Imlib_Image tns_scale_down(Imlib_Image im, int dim)
+static Imlib_Image tns_scale_down(Imlib_Image im, int dim)
 {
 	int w, h;
 	float z, zw, zh;
@@ -374,7 +374,7 @@ void tns_unload(tns_t *tns, int n)
 	}
 }
 
-void tns_check_view(tns_t *tns, bool scrolled)
+static void tns_check_view(tns_t *tns, bool scrolled)
 {
 	int r;