Retire the precompiled/ support

It was in a time long past that we tried to solve the problem Maven
solves so much more beautifully: avoiding the need to build everything
from scratch, but rather get trusted builds from a repository of
artifacts.

It is high time that we stop supporting that backwards-compatibility
wart.

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Start refactoring the source code

We start by factoring out the string, allocation and the common
functions (error, die).

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Organize #includes

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Avoid global variables

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Move prefixcmp/suffixcmp into common.h

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Move mystrlcpy() into string-funcs

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Move the PATH_MAX definition into common.h

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out file functions

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out functions relating to the Java home

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out the splash-screen code

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>
Factor out platform-dependent code

Signed-off-by: Johannes Schindelin <johannes.schindelin@gmx.de>