Officially introduce amalgamated builds (#4416)

Remove redundancy between all-in-one and all-in-one-source builds
by keeping only the second, and adopt the more established term
"amalgamated" build for it. This change includes the following:

- Replace `ENABLE_ALL_IN_ONE` and `ENABLE_ALL_IN_ONE_SOURCE` cmake
  options with `ENABLE_AMALGAM` top-level option.
- Replace `--all-in-one` option of `build.py` helper with
  `--amalgam`.
- Merge the `srcmerger.py` and `srcgenerator.py` tool scripts into
  `amalgam.py` (with improvements).
- Update documentation.

JerryScript-DCO-1.0-Signed-off-by: Akos Kiss akiss@inf.u-szeged.hu

docs/01.CONFIGURATION.md

@@ -5,16 +5,19 @@ A configuration option's value can be changed either by providing specific C pre
 This document lists the available configuration options, shows the configuration name for C, CMake, and python, and provides a brief description that explains the effect of the options.
 
 
-### All-in-one build
+### Amalgamated build
 
-Enables the All-in-one build process, which aggregates the contents of each source file, and uses this combined file to compile the JerryScript library.
-This process can provide comparable results to link time optimization, and can be useful when LTO is not available otherwise.
+Enables the amalgamated build process, which aggregates the contents of each source file per library
+(i.e., JerryScript's core, port, and math libraries), and uses these combined files to compile the project.
+This process can provide comparable results to link-time optimization, and can be useful when LTO is not available otherwise.
 
 | Options |                                              |
 |---------|----------------------------------------------|
 | C:      | `<none>`                                     |
-| CMake:  | `-DENABLE_ALL_IN_ONE=ON/OFF`                 |
-| Python: | `--all-in-one=ON/OFF`                        |
+| CMake:  | `-DENABLE_AMALGAM=ON/OFF`                    |
+| Python: | `--amalgam=ON/OFF`                           |
+
+See also: [Amalgamated sources](#amalgamated-sources)
 
 ### Jerry debugger
 
@@ -278,18 +281,20 @@ This option is disabled by default.
 | Python: | `--mem-stress-test=ON/OFF`                   |
 
 
-# Single source build mode
+# Amalgamated sources
 
-There is a special mode to use/"build" JerryScript. That is generating a single C file which can be
-included into projects quickly. To achive this the following command can be executed to create
-a set of files into the `gen_src` directory (Note that the command is executed in the jerryscript root directory
-but can be adapted to run outside of the project root dir):
+The sources of JerryScript can be combined into a handful of files to allow their easy integration
+in other projects. To achieve this, the following command can be executed to create a set of files
+into the `amalgam` directory:
 
 ```sh
-$ python tools/srcgenerator.py --output-dir gen_src --jerry-core --jerry-port-default --jerry-math
+$ python tools/amalgam.py --output-dir amalgam --jerry-core --jerry-port-default --jerry-math
 ```
 
-The command creates the following files in the `gen_src` dir:
+(Note: In the example above, the command is executed from the project's root directory, but that is
+not mandatory.)
+
+The command creates the following files in the `amalgam` dir:
 
 * `jerryscript.c`
 * `jerryscript.h`
@@ -304,15 +309,15 @@ should be adapted to the required use-case. See the file contents for more detai
 default configuration. (Note: This config file is created from the the `jerry-core/config.h` file.)
 
 These files can be directly compiled with an application using the JerryScript API.
-For example with the following command:
+E.g., using a command similar to the one below:
 
 ```sh
-$ gcc -Wall -o demo_app demo_app.c gen_src/jerryscript.c gen_src/jerryscript-port-default.c jerryscript-math.c -Igen_src/
+$ gcc -Wall -o demo_app demo_app.c amalgam/jerryscript.c amalgam/jerryscript-port-default.c amalgam/jerryscript-math.c -Iamalgam/
 ```
 
-Please note that the headers must be available on the include path.
+(Note: The headers must be available on the include path.)
 
-In addition there is a `-DENABLE_ALL_IN_ONE_SOURCE=ON` CMake option to use this kind of sources during the build.
+This approach is also under the hood of the [amalgamated build](#amalgamated-build) process.
 
 # Target specific information