Ivan's contribution to GMT 3.2

Logarithmic axes patch

I would like to propose two new features for the axes annotation in the GMT.

1st: In astrophysics, we often work with great ranges of values (many orders of magnitude). This requires to use logarithmic axes with large steps of tic marks and their annotation, with log10(step)=2,3 and even more... However, GMT 3.2 allows to plot annotations for log10 axes every integer log10 value or even more frequently. The proposed patch allows to specify large steps for the log10 axes, in the form illustrated by an example below.
2nd: 10^0 instead of 1, and 10^1 instead of simply 10 do not look beautiful. This is also fixed by the proposed patch.

An example:

     
  psbasemap -JX8l/8l -R0.1/1e8/1e-15/1e15 -Bf3a100p/f1000a1000p > example.ps

The patch is here.

Makefile for Linux with shared library

The dozens of GMT utilites contain much common code, so one can save the diskspace by linking them dynamically. The proposed makefile makes a shared libraries libgmt.so.3.2 and libpsl.so.3.2, and links the utilites over them. After that, the disk usage by GMT utilites reduces remarkably.